Re: is this true?
As I understand it, the fragmentation of android is that it has too many different resolutions and os versions on different phones. Which means when a developer writes a software he has to write it such that the software works on all devices, which is very difficult. Bring in the fact that in each resolutions there are devices with different os versions, that increases the number of unique devices for the developer to address. As for WP however there are only 4 different resolutions and two different os versions, totalling to 8 unique combinations. However incase of android the combinations are very high to address. Hence any single app cannot address all the unique combinations, that's uncontrolled fragmentation. However iOS developers have to address only one single resolution all along and now two resolutions only, hence developers love working for iOS. However that left iOS with limited choices in phone sizes. So WP is some where inbetween iOS and Android with a balance between choices and easy development. So WP is not fragmented and will never fragmented if the new 18 month update support promise of microsoft is followed. That's my 2 cents...
This is all good, but I will offer one correction and other added thoughts... The correction is that until Microsoft adds 1080p, which won't really be a surprise, there are only three resolutions. 480x800 (WP7x devices, 822, 8s, and low-end Lumias), 1280x768 (922), and 1280x720 (8x).
As for developing, a developer does not *have* to develop covering all three resolutions. If he only writes for one, the app will work. It may not look the same, but it will work. The easiest way, in my opinion (and the way I'm doing it), is instead of laying out the screen by pixels is to do it by ratio. My apps will look the same on all three screens, and all I had to do to cover them all equally was to check a couple of checkboxes. Otherwise, I believe you'll get the black bands at top and bottom of the screen. Now I'm referring to the xaml apps, or apps that are laid out using xaml, which most of your non-game apps are going to be, at least for now (there are a couple different ways to develop for the phone). I've only used this method of developing for the phone, so I can't speak for the others. I'm also not speaking for games, as I've never developed one. Basically, though, the phone will adapt if the developer didn't.
As for the fragmentation between WP7 and WP8, yes, there is fragmentation in that respect, because anytime you add capabilities to something, the old equipment won't run the apps that use those capabilites. WP8 will run *most* WP7 apps without any problems, but making apps for WP8 that will run on WP7 is more of a challenge.