While Marissa Mayer is busy trying to figure out what to do with Yahoo’s new $4.5 billion in cash — recently gained from selling 20 percent of its holdings in Alibaba back to, well, Alibaba — the Chinese web and eCommerce giant has recently been in a heated exchange with Yahoo’s old pal, Google.

The fun apparently began after Taiwanese PC maker Acer cancelled the launch of its new phone in China — an event for which there was quite a bit of anticipation. As things progressed, it became clear that, in fact, Google was at least partially responsible for delaying the launch of the phone. Why? Long story short: Google objected to Acer using a rival OS in its new phone, according to the WSJ.

The rival OS in question is, of course, Aliyun — Alibaba’s first self-developed mobile operating system. Naturally, Alibaba was none to happy about Google’s apparent interference. In frustration over the exchange, Alibaba VP John Spelich told TechInAsia: “Will someone please ask Google to Define Android?”

I like to picture this quote in caplocks, preceded by an exclamation like “GAH!” and a double-handed cheek smack. Not just because I’m a member of the media and I enjoy good drama (no, you can’t have any of my popcorn), but also because I think there are a number of people who might agree — if not with this statement — with the sentiment. Maybe this will be impetus for Android to take a page out of Firefox’s book and get trademarked (while remaining open sourced).

But, wait, what’s the backstory here? Well, I’m glad you asked. In the same WSJ story referenced before (unfortunately and somewhat ironically, it’s behind a paywall), but Google’s reason for meddling in Acer’s Aliyun launch was, of course, that Acer had totally given it a promise ring and because Aliyun is playing fast and loose with Google’s mobile things (i.e. it’s not compatible):

[Acer has] committed to building one Android platform and to not ship non-compatible Android devices … Compatibility is at the heart of the Android ecosystem and ensures a consistent experience for developers, manufacturers and consumers. Non-compatible versions of Android, like Aliyun, weaken the ecosystem.

So, basically what Google is saying is that Aliyun is running a non-compatible version of Android. And, hey, if that’s true, Google has a very good reason to rain on Acer and Aliyun’s parade. Clearly, trying to take the high road, Android published this nicely written little run-down of compatibility earlier today. The biggest takeaway: The most important external factor that, in Google’s words, can weaken the Android ecosystem as a whole is “incompatibilities between implementations of Android.”

And, again, this makes sense. The chain is only as strong as the weakest link, if some developer implements a utility function poorly, then apps don’t run as well across devices, consumers get a bad user experience, developers leave — you get it, the thing falls apart.

Okay, so the blog post is a veiled way of saying, “Quit making the system suck.” Of course, it does betray a little sour grapes from Google, which doesn’t make any money yet from Google Play in China, and was clearly not happy with one of its OEM partners using a competitive OS, even if “incompatible.”

Android Top Dog Andy Rubin weighed in tonight on his Google+ profile (which is getting ridiculous, by the way … thank god Dick Costolo doesn’t respond to every question in a tweet), saying that he/Google were very surprised by Alibaba’s CSO Zeng Ming quote that Aliyun “wants to be the Android of China,” especially when, Rubin says, the “Aliyun OS incorporates the Android runtime and was apparently derived from Android.”

Take that, Aliyun. Rubin 1, Aliyun 0. He might as well have just said, “but wait, Android is going to be the Android of China, whether you like it or not.” After all, Android already has 68 percent of smartphone sales there.

Rubin continued:

Based on our analysis of the apps available at http://apps.aliyun.com, the platform tries to, but does not succeed in being compatible.

It’s easy to be Android compatible, the OHA supplies all the tools and details on how to do it. Check out this blog post that explains how we think about compatibility and how it relates to the ecosystem we worked hard to build. [He then links to the “compatibility” blog post.]

Google victory, right? Well, er, sort of.

Apparently, Google had been pressuring Acer to call off the event for awhile, as this wasn’t the first phone that launched with the supposedly forked Android OS. Also of not here, apparently Acer (as an OHA signatory) agreed not to market/implement an Android fork that is not Android compatible. SO, there’s that. Not a surprise then that Acer’s attempt to launch an Aliyun smartphone didn’t sit too well with Google and that it would try to enforce this agreement.

Of course, at the root of this is the compatibility issue, and whether or not Aliyun is an offender to begin with — whether or not it’s actually a forked Android OS at all. To that point, Aliyun claims that its OS is built from the ground up and is Linux-based, so it’s technically not part of the Android ecosystem. Meaning, then, that it wouldn’t be beholden to dealing with OHA regulations/requirements.

As John Spelich said in response to Google’s statement and then later added to his thoughts in a quote in TIA:

Aliyun OS is not part of the Android ecosystem so of course Aliyun OS is not and does not have to be compatible with Android. It is ironic that a company that talks freely about openness is espousing a closed ecosystem.

…

This is like saying that because they own the Googleplex in Mountain View, therefore anyone who builds in Mountain View is part of the Googleplex.

Of course, Aliyun is trying to play both sides — remain separate from the Android ecosystem, while being Android binary-compatible. Although it does say its focus is on web apps. Obviously, what tipped off Rubin (as he alludes to in his Google+ post) and Google was the fact that Aliyun is running Android apps. It can’t have it both ways, so if it drops the APK, perhaps Google wouldn’t block the rim…

It’s obviously somewhat of a mess, and Google certainly doesn’t seem to be eager to back down, and Aliyun is staying firm in the fact that it’s NOT actually a forked Android OS and therefore Google is being unreasonable in its demands. If you side with Aliyun in this debate, given Google’s tireless championing of “open” technology, it would be hard not to see the company’s actions as at least a little bit hypocritical in this context. Especially given that this makes Google look like it’s trying to “control” its ecosystem. Probably because it is. Understandable? Yes. As “open” as Google claims? Probably not.

As Jon mentions, Google’s policy on incompatibility is, at the very least, inconsistent. If you take the opposing view, that Aliyun is actually guilty, then one could contend that Google should have enforced the same takedown for Haier, which could be subjet to the same “Android forked OS” (or incompatibility) accusation.

At any rate, I think we can now be sure that Samsung won’t be bringing its own forked OS to the table anytime soon.