Because I'm currently dealing with GPL-FUD in a discussion again, here's the appropriate link to an explanation of why GPL is not a viral license with contractual character, but simply one thing: a license for the use of source code.
Incorrect use of GPL source does not automatically make the new project GPL as well. The reverse path is indeed correct: if you want to use GPL software as an integral component, then your project must also be under GPL. But that effect works in exactly only this direction. Incorrect use of GPL source at worst only leads to one thing: the withdrawal of the license to use that source. So the project simply has to do exactly what it should have done anyway: write the corresponding part itself.
Equally absurd is the claim that you give up your rights to your source code when you contribute it to a GPL project. Of course you retain all rights to your own source code. My experience with arguments of this direction: I'm not contributing to the project because it's under GPL and therefore I can't freely use my own source code anymore are just lazy excuses for what is actually the case: I'm not contributing to the project because I can't freely use your source code for my other projects because my projects shouldn't be GPL. And that's something entirely different - nobody takes away your rights to your own source code (unless you explicitly give them up - in the context of official GNU projects it's customary to transfer rights to the FSF). But you don't automatically gain rights to other source code just because you contributed something yourself. And another thing: people who threaten that their great innovative ideas won't go into a project because it's under GPL usually don't have anything really innovative to deliver anyway. Actually, the number of innovative contributions to projects is minimal anyway - and strangely enough, the people who really deliver innovative parts have the least problems with the license...