If you are using WordPress for your blogs (and who isn't) then please take note to make sure you are using the current installation of WordPress, which is version 2.5.1
There are an increasing amount of blogs, all with ver 2.3 and earlier installs getting "hit" by the well known iFrame exploit that infects website visitors with a trojan download.
Well known Internet Marketer Stu McLaren now has an infected blog: