I think the correct question for Android users (and I am one, so I somewhat already know the answer), is this:
How many Android manufacturers is willing to upgrade at least one of their handsets' software by two major versions? (2.0 to 2.1 to 2.2 does count)
Manufacturers? I think if you look through all the major Android handset manufacturers, you can find at least one phone from each that has received two major updates.
My old phone, a Samsung Epic, shipped with 2.1 (despite 2.2 already being out at its release) and later received official updates to 2.2 and 2.3. Of course, unofficial releases of each version were available months before the official OTA updates, and there are several ICS-based roms available for it now.
Similarly, my wife's old phone, an HTC Evo 4G, shipped with 2.1 and later received updates to 2.2 and 2.3.
I know the original Motorola Droid shipped with Android 2.0 and received updates to 2.1 and 2.2.
Not sure if there are any LGs that have gotten two major updates. All (or most) of the Optimus One variants shipped with 2.2 and received updates to 2.3, and the Nitro HD shipped with 2.3 and is upgradable to 4.0.
I think, in general, most higher end Android phones get at least one update, if not two. In many cases, though, that first update just brings it in line with what it SHOULD have shipped with - for instance, the Motorola Droid RAZR MAXX came out a while after the Galaxy Nexus but shipped with Gingerbread anyway and STILL doesn't have an ICS update.
For comparison, Apple doesn't really make "low end" iPhones. They just continue selling the old versions for a while. So an iPhone 3GS purchased today won't get as many updates as a 4S bought today, just as a low end Android phone bought today won't get as many updates as a high end one.