Tools to run an URL Shortener on your own Domain

Won't twitter replace your URL with a bit.ly one anyway?<p>(There are other use cases for URL shortners. I'm just commenting on this specific one.)

There also is an open source solution for that: <a href="http://urlshort.sourceforge.net/download/" rel="nofollow">http://urlshort.sourceforge.net/download/</a>