I've talked with ZodTTD about this, but I've also done my own research into the licensing claims. What I've found is that most of his Cydia (and, presumably, Android) apps do rely on at least one GPL-licensed component. Note, however, that he can sell GPL'd apps, and the GPL specifically allows this: he just need to release the source code (edit: or give it to people when they ask).
However, looking at his GitHub, his source releases are not timely (although they do seem to be complete). If ZodTTD just added "dump source to GitHub" as part of his release process, there would be no issues here. I don't think ZodTTD is deliberately trying to steal money or code from anyone, but I think he misunderstands the importance of putting out the source code for his emulators right away, as they are released to a store.
(However, there is one exception: SNES9x has a license specifically forbidding commercial use. ZodTTD's "snes4iphone" then does, in fact, either need to be taken down or (at least?) made free from now on.)
> I think he misunderstands the importance of putting out the source code for his emulators right away
The GPL does not require this.
The GPLv2 says this:
a) Accompany it with the complete corresponding machine-readable
source code, which must be distributed under the terms of Sections
1 and 2 above on a medium customarily used for software interchange; or,
b) Accompany it with a written offer, valid for at least three
years, to give any third party, for a charge no more than your
cost of physically performing source distribution, a complete
machine-readable copy of the corresponding source code, to be
distributed under the terms of Sections 1 and 2 above on a medium
customarily used for software interchange; or,
(choice c is only available for non-commercial releases).
Note (b): you do not have to provide the source code on a public server, nor do you have to do so immediately. The requirements are:
1. A notice that source code is available for three years upon request
2. That requests for source code be honored at cost
If nobody ever requests your source, you're still compliant with the GPLv2 if you never release it.
edit: and note that, for a commercial product, you only have to honor customer requests.
Nothing in the GPL states that the source has to be posted online at the time you release a binary, what it states is that you must provide it to customers (people who have/use your binaries) at their request.
And they don't release a buildable or complete copy of the source (more info: http://news.ycombinator.com/item?id=2530689). But, ZodTTD's emulators aren't in the App Store since Apple won't allow them, so that's not really relevant here.
However, looking at his GitHub, his source releases are not timely (although they do seem to be complete). If ZodTTD just added "dump source to GitHub" as part of his release process, there would be no issues here. I don't think ZodTTD is deliberately trying to steal money or code from anyone, but I think he misunderstands the importance of putting out the source code for his emulators right away, as they are released to a store.
(However, there is one exception: SNES9x has a license specifically forbidding commercial use. ZodTTD's "snes4iphone" then does, in fact, either need to be taken down or (at least?) made free from now on.)