Ironport has a list, updated daily, of the top spam sources from around the world. I meandered on over today to take a look and one thing jumped out at me which I have highlighted below.
If you can't read that, it is IP address 188.8.131.52. The hostname is mail.fiedom.org, and the network owner is ColoGuys.
ColoGuys? What? As in Colorado Guys? Or maybe it's McColo Guys, the guys who ran McColo?
The WHOIS information says that the domain was registered on March 15, 2009 (three days ago). The contact information is protected (usually a bad sign), the admin address is a PO Box and it was registered in a location in The Netherlands.
I'm not saying that this means that these are the same guys who got shut down four months ago, but from where I am sitting and typing, it sure looks suspicious.