Also, per the twitter developer guidelines, you need to parse the tweets and make all links, hash tags, and usernames hyperlinks back to twitter for those individual items.

I recently had to do a similar thing for a site I threw together to get my sporting news in one location (http://sportszealots.com). It's very hacky code written very quickly (in ruby), but if you'd like it send me an email and I'll send you back what I have.

EDIT: Well damn, I didn't know about the handy utility mentioned below...that's definitely better solution!