malware web page scam today

A friend had a link is its twitter: http://bit.ly/mcHjaZ and when I followed the first time I ended in a malware scam page, that was very convincing. (The second time onwards I was directed to the right page)

I do not know if it was something to do with bit.ly or twitter or the target page (probably the latter), but the page title in the the browser tab was the same for the original linked page. I assume that this is a hijacking javascript injection in the web server of the target page:

[not put as a link to prevent cliking ;-)]
http://dornob.com/mind-warping-wood-folding-chair-looks-curved-packs-flat/

Very frightening.

[update]
Thanks to Karen from my Systems Team here there is a more detailed explanation
http://www.snipe.net/2011/05/rogue-mac-antivirus/

[update 2011-05-30]
Apple has created an entry about this in support.apple.com:


How to avoid or remove Mac Defender malware