I could be wrong, but I don't think the Android store applies any blanket license to downloaded apps, besides the implied "you may download and use this app". The disagreement here is that Apple adds a license to all apps that says you aren't allowed to decompile or reverse engineer them (among other things), and the GPL doesn't let anyone but the copyright holder add those kinds of additional restrictions.
5.4 You grant to the user a non-exclusive, worldwide, and perpetual license to
perform, display, and use the Product on the Device. If you choose, you may
include a separate end user license agreement (EULA) in your Product that
will govern the user’s rights to the Product in lieu of the previous sentence.
So it sounds like Google doesn't add any new terms to apps besides whatever the app authors themselves say, so GPL apps are fine.
Also, the users are free to obtain the source code recompile and run it on their phone at any time. While the iPhone requires a SDK license to be able to distribute the software to the phone and can only do so through the app store. I think this is their problem with apple and GNU Go. There is no way for the user to modify the application and run it on their phone.
No - requiring a commercial compiler & sdk wouldn't be a problem - this is a licensing issue - the terms under which the author of the iPhone application is re-distrubiting the app, through the iTunes store, cannot be possible under the terms of the GPL - so the author had no right to do distribute it in this way in the first place.
You can write and trade GPL software on proprietary platforms, even platforms other people may never have access to - as long as you aren't contractually restricting them from re-using the code.
But again, it hasn't been made explicitly clear which terms are being violated. The GPL doesn't require that code be distributed along with binaries, only that code be made available upon request, and the manner for doing so be made clear. There's nothing about app store which prevents that.
The section 7.2 clause in the SDK agreement seems troubling, but it also seems unenforceable. Not only have lots of people blatantly chosen to ignore this provision (see Wordpress), it doesn't seem like it would hold up under copyright law (but I'm not a lawyer).
It's not a source code issue. The GPL prohibits you from adding restrictions to further redistribution. The App store adds the restriction that you're not allowed to redistribute. Seems pretty clean cut to me.
The Android developer distribution agreement says (http://www.android.com/us/developer-distribution-agreement.h...):
So it sounds like Google doesn't add any new terms to apps besides whatever the app authors themselves say, so GPL apps are fine.