There's a new worm in town: WORM_SOBER.AG. This baby is toxic and can self propagate. You have to execute it to install it on your system, though. So far, it has been spread through emails puporting to come from the CIA or FBI, claiming that you've been detected "visiting over 30 illegal Websites." You're then asked to download and answer a questionaire. The other version hides as videos of Paris Hilton and Nicole Richie.
I'm sure I don't need to say it, but don't download anything you receive in an email, even if it sports an fbi.gov or cia.gov address. Trust me, if the CIA wants to contact you, it won't be by email. That's what tinfoil helmets are for.