Interesting. I have seen similar things for Perl, and also Apache when you have proxying enabled.
The sucky thing is that of course, its usability is limited. You can't really use it for nefarious purposes, since the IP address will always be your server's.
I'll post some perl IP spoofing code here later.. for nefarious purposes.....
If you can do a three way TCP handshake with Perl, I'd be interested in how. I've been able to affect it with some netcat scripting, but it's hard. It requires a bit of extra knowledge about loose routing and RIP. A bit of a "sideband" sort of approach to the whole thing.