As far as I know, this particular worm is only active on twitter.com - and although it could redirect you to a malware site, I've seen no reports of that.
TechCrunch has just produced a five point program to deal with the mouseover worm:
1. Donít use the Twitter web site, especially the older version.
2. Use a desktop application like Tweetdeck, Seesmic or similar. Although the affected tweets do appear in your stream, they will not produce the same mouseover effect.
3. Use the Twitter mobile site, which appears to be unaffected.
4. Delete the affected tweets by avoiding the main web site and logg-in to the mobile site instead. Then delete the forced Retweet. Delete any tweets so that the worm does not spread to your friends and followers.