Again, from October, but still funny:
Got a phone call late this afternoon from another sysadmin. Seems that every printer in his building was spitting out paper with a couple lines of gibberish on each page (a feature of the Bugbear worm). He thought that he'd covered all of his bases by having a firewall and up-to-date virus scanners.
Turns out the infection vector was one not planned for: web-based e-mail.
Yet another reason to ensure your users are NOT using web mail services which do not have virus scanners/content filters.