There are a number of updates on Twitter urging users to download a file called "tweetdeck-08302010-update.exe" from a URL beginning with http://alturl.com/.
These tweets are from hacked accounts and this file does not come from TweetDeck. Do not download it!
The fake updates often being with one of the following phrases:
Official updates are exclusively available at: http://www.tweetdeck.com/desktop/