Eish, I'm afraid... My first post in an Android thread. cerebus is 100% correct as far as fragmentation goes, it really has nothing to do with not having Siri on the 4 or 3GS. From an Apple owner's perspective, whether you have a 3GS, 4 or 4S your IOS5 experience is pretty much identical and while the 3GS might be old tech, the phone itself is still a viable proposition for owners 'cos the OS is brand new. By the time IOS 6 is launched, support for the 3 might end but it will have had a really, really good run, much longer than most people's two year contracts and that boys and girls is real value from that profit machine called Apple.
Also, as far as mercurial's Android dominating markets thing goes... I don't think you'll find an Apple fanboy who'll disagree with you... but... The three top selling devices during that Oct/Nov period were the 4S, 4 and 3GS. Some of us, and Mr. Tarrant apparently, do like to point out that on a device-to-device level (iPhone 4S vs. SGS2) the iDevices win. There are a whole galaxy ('scuse the pun) of Android devices out there while Apple have three phones and the iPod... Of course there are going to be more Android activations overall but phone vs. phone, the winner is in the Apple corner... Them's the facts.