spoofed, random numbers e-mail?

The other day, Jessica, on her Gmail account, received a message purportedly from herself, and to herself. The subject line was "586876" and the content was "5556." There didn't seem to be any attachment or hidden text.

This morning, I got a similar message - to me, from me - but on my work e-mail account. The only difference was my subject line numbers of "455."

I've found a few blog posts from people getting the same thing, a thread on the Google Groups Gmail discussion board (although most of them seem to think it's solely a Gmail problem, which it clearly isn't), and a post from the Internet Storm Center. (The Internet has a Storm Center?)

Anyway, I'm putting this post out there in case more people start searching blogs, as I did, to see if it's a more widespread problem. If you get a message like this, or come up with any additional information, please post in the comments. Thanks!