There is no magic fairy dust protecting Macs - Dai Zovi, security researcher and co-author of The Mac Hacker's Handbook.
This malvertizement is *very* new
Cite - Kimberley's site - she has all the details:
http://www.bluetack.co.uk/forums/index.php?s=8085d39a6043e446198cbd9ab8234f01&showtopic=18064&st=30&p=86950&#entry86950