I think by the end of the year this will be less of a problem. Consider that last year two OS versions were released and the first was Honeycomb which had a very binding legal agreement associated with it so as not to appear on phone form factor devices. Then Icecream Sandwich comes out and as usual most of the Android ecosystem does not see any of the codeline until the AOSP release. So now it's 3 months down the road.
In the biz. I haven't heard of any significant handset vendors starting a Android phone or tablet project in 2012 on anything but 4.0. So with the growth in the market expect 4.0 to grow very quickly and perhaps consider 2011 to be a oddity.
The only relationship between the version of the OS and fragmentation is that a new OS rev usually introduces an additional API level. So if you write an app to API level 15 (4.0 IIRC) that will be available and work on subsequent revs.
I think you're missing the point. Putting it another way: When the 4.1 APIs are released, how long do you need to wait to add 4.1 as a dependency for the core cool new feature in your app? Obviously you can use the 4.0 APIs that are still there, but you have to admit that your ability to push new features to your whole user base is impeded by the rag-tag update schedule.
Yes I agree that you cannot target the the latest API, and there is a lag, which has been exceptionally long because of the Honeycomb blip.
But it just means that, form factor and to a certain extent performance differences are more likely to be a problem than perceived platform level fragmentation IMO.
Eclair took about 9 months to peak, Froyo about a year, Gingerbread still looks like it hasn't peaked about 15 months since release.
To fix fragmentation, you want everybody on the same page. If they are releasing new features each major version, then I suppose this means you want them on the same major version.
At this rate, you will not see progress until maybe Q2 2013 when everybody is releasing ICS phones.
In the biz. I haven't heard of any significant handset vendors starting a Android phone or tablet project in 2012 on anything but 4.0. So with the growth in the market expect 4.0 to grow very quickly and perhaps consider 2011 to be a oddity.