The newest virus circulating is the UPS Delivery Failure. You will receive an email from UPS Packet Service along with a packet number. NOTE: The word packet is mis-spelled on this line. It will say that they were un-able to deliver a package sent to you on such and such a date. It then asks you to print out the invoice copy attached. DON'T TRY TO PRINT THIS. IT LAUNCHES THE VIRUS! Pass this warning on to everyone.
http://www.ups.com/content/us/en/about/news/service_updates/fraud.html
http://www.snopes.com/computer/virus/ups.asp