Fox Says Web Bugs == Virus Risk
A virus that used the Web bug technique could essentially conduct a poll of potential victims to determine whether or not they would be good targets.
Woop-de-doo. It's not expensive to sneeze viruses all over the world, so why bother targeting? And the majority of the world - present company excluded - uses Win32 and IE - or IE-based AOL. You don't get a hell of a lot more useful info out of your basic HTTP headers than that.
The profiling is disgusting. The increased threat of virus is negligible.
If anything, the thing that opening the email does is advertise "I'm an idiot. Here's my IP address. Crack my system. (Hint: I'm the kind of person whose password is the same as my username)."