Well Twitter has its own shortener t.co, and when you tweet one of those Twitter displays the true link abridged (for example "www.abandonia.com/vbull..."). Although t.co is designed to be used only by the tweet button, it's very easy to "hack" the URL API:
Code:
http://twitter.com/share?url=%s
Replace "%s" with any URL. I've stored it as an Opera "search engine", so I type "tweet ..." into the address bar--or rather I type "tweet " in front of any URL I'm at and want to tweet--and presto. BTW there's little point in using t.co outside a Twitter post, only there it has the advantage of seeing the true link.