I also just looked up the correct punctuation usages for "it's" and "its." Let me expound for those of you which find this confusing (don't worry, I do, too):
it's - a contraction for "it is"
its - the possessive form of "it"
I realize that this flies in the face of putting an apostrophe s ( 's) at the end of a word we want to make possessive, but that is the english language for you.