I just received an email about a "dangerous" virual postcard going around. I automatically check on a hoax/urban legend site to verify things before I pass them on... I've been burned too many times in the past. It looks like this could be for real. You can check here or I would urge you to google some key phrases to check for yourself.
The subject line says something similar to a family member has sent you a postcard. When you open the email and click on the link (which looks legit) it takes you some place else and you're zapped with a virus. It also sends more emails out using your address book.
So be very leary even if the greeting message looks like its from someone you know.