Three managed email servers that I run just got spiked with hundreds of these in the last hour.
Variants of the subject line include:
You've received a postcard from a family member!
You've received a postcard from a friend!
You've received a postcard from your wife [/husband /spouse]!
This is how "zombie" systems are created. With a solid zombie PC network under their control, professional spammers can send out those millions of canadian drugstore/viagra/penis enlargement e-mails you get daily.
There's always a temptation to open a suspected attachment when you've got good virus scanning software installed. DON'T!!!:
Perhaps the most dangerous part is that, when SANS ran it through 30 different anti-virus programs, only a quarter of them picked up ecard.exe as a suspect download.
The goal of the virus programmer is to come with stuff that commercial virus scanners aren't aware of.
Just. Don't. Open. It.