.9999. . .

So, I hear that the question as to whether .999 . . . (repeating) is equal to one is a commonly discussed online question. Although this is apparently most typical among the online gamers. I was wondering whether there are any other math dorks out there who have an opinion on the matter. I know that I solved it in one of my math classes, and just need to hunt up the proof, so in the meantime, any comments, questions or thoughts?