Lengthening URLS

I’m planning on publishing tweets from Twitter on my blog. This all works ok except for one thing. I need the URLs to be lengthened so that for example I can use a music player plugin around any mp3 links that I tweet.

I tried to create a wordpress plugin for longurlplease so that before saving to database any shortened urls get expanded. However I’m having some javascript problems with that so I am looking for any existing solutions rather than my own.