Not an even comparison. If you really want to compare, then have a look at updates for Nexus devices.
My iPhone 4 can get iOS 7 today. That's as old of a device as a Galaxy S or S II I believe. I'm pretty sure that the S and S II are both in Android 2.2 or 2.3 land.
It's a side effect of the two different approaches to ecosystem for sure, but it's not an unfair comparison.