Well I've been wondering about the implications myself. The GPL is pretty strict about what you're allowed to do with GPL'd compoments without making your whole product GPL licensed.
I'm actually trying to buy one of those games right now just to see what they are, but so far I wasn't able to log into my new AmiPass account (which you have to do to check out from the shop). It won't accept my password and I haven't gotten my e-mail to change the password yet (requested it through the website).
Does anybody have a working account on there? I'm starting to think it's all fake.