I have all of my code on github under a CRAPL license [1]. It assumes a certain amount of good-faith from others, but I feel that if you're worrying about getting scooped, your problem isn't ambitious enough. Luckily, my adviser agrees, and is very in favor of open releases of data [2].

[1]http://matt.might.net/articles/crapl/ [2]http://www.michaeleisen.org/blog/?p=440