There're dozens and dozens of interesting resources about Android Fragmentation out there, so here's a list of a few of them:

An Introduction to AndroidFragmentation.com
Slides presented on ther German droidcon Conference on May 27th. There's some very interesting data in there, check it out.
http://www.slideshare.net/j.ritter/androidfragmentationcom-an-open-community-project

Doomed To Eat Donuts Forever – The Behold II Won’t Be Upgraded Past 1.6
Posted by Chris Dehghanpoor in Behold II
http://www.androidpolice.com/2010/05/29/doomed-to-eat-donuts-forever-the-behold-ii-wont-be-upgraded-past-1-6/

Platform Versions - Statistics reported by Google:
http://developer.android.com/resources/dashboard/platform-versions.html

Open Embedded Software Foundation - a Japanese consortium of industry giants who intend to push Android into a wide range of different devices and verticals. It's a brilliant project and I very much hope they'll accomplish their goals. Here's a briefing on their project. It does not talk about fragmentation but, as a matter of fact, the nature of their project fosters it (for very good reasons):
http://docs.google.com/viewer?a=v&q=cache:dsW_xu3oZ30J:www.oesf.jp/modules/download/index.php%3Fpage%3Dvisit%26cid%3D21%26lid%3D101+computex+2010+%2Bosgi&hl=en&pid=bl&srcid=ADGEESjHEJuagAhziKcXoWf82to0ysSTbegtoH2sj8jVPWLr3G0oTW_HHoGnzBw7NjIPqgO92JB-LXTS1fy1Gp4xHK7s44ZWPGV7XLityNIsRuMmwij6nrzMnOhwTxOtLtleawNdgjZ-&sig=AHIEtbTVuQcLYkFnT4brc4Lkefn452WaMw