Thanks Yoddler and Factory for your comments on potential legal issues.

I will certainly check them (once again). This will however not effect the competition (at least the first part):
1) The author of the logo selected by the bitcoin-app.com users will be awarded with 1 BTC.
2) Another 1 BTC for the author of the logo that I do finally make the new bitcoin-app.com logo.

(1 and 2 might be the same)