I’m using Google Code to host my application code, its conveniant and the SVN repository means I don’t have to worry about backups
When you create a project on there you need to select a license, I chose GNU GPL v3.
By doing so, does that prevent me from selling my application on the Android market place?
It doesn’t prevent you selling it, despite the license you still own the code and can issue it under whatever licenses you so desire. It does mean that anyone can take your code, compile it and install it on their Android without paying you a penny but that’s probably a small portion of those who might want a good app.