The original plaintext tweet:

A link: http://grahamswan.com. An email: thinkswan@gmail.com. An @-mention: @underexperiment. A hashtag: #jquery.

The tweet after being run through twitter_autolink():

A link: http://grahamswan.com. An email: thinkswan@gmail.com. An @-mention: @underexperiment. A hashtag: #jquery.

The raw output of the autolinked tweet: