Ars Technica's "Google's Iron Grip on Android: Controlling open source by any means necessary" is an interesting look at some of the problems that Google faces with Android and some of the strategies they've had to employ along the way.

Google has had to take a very interesting position with Android because they didn't really want to be in the mobile phone business, they just want to protect themselves from the Mobile business changing the business they are in too drastically. Google's business depends on the health of the web, and Google's place in that.

In order to protect their position, Google doesn't want to rely too heavily on the goodwill of others, any more than Apple does, although I don't think that's as ingrained in Google's DNA as Apple's. Android, for Google, is about ensuring that they have a say in the evolution of the mobile phone and mobile device market and how that has an impact on Google. They were willing to give away a fair amount of value in this new market as long as it helped to support Google's existing business.

Exerting enough control over an open-source project to meet your own objectives is a tricky thing, and Android has always had to walk that line carefully by being a hybrid of open and closed source models. Much of the development of new versions of Android is done completely in the dark, with code only being open-sourced near the release date. Portions of the overall Android experience are wholly dependent on proprietary closed-source Google applications and services which are only available to you if you meet certain conditions. You can build an Android device without these, but not without a significant investment in filling these holes.

The emergence of out-and-out-forks that do exactly that has encouraged Google to continue to seek more leverage over the Android ecosystem by moving features into closed-source applications and tying them to Google services, which they can control more completely.

Ars Technica has done a typically solid job of covering those problems and some of the solutions Google has employed, and it's a worthwhile read.