If you have noticed some strange activity coming from my IP address regarding session hiccups and bad referrer URL's, I've been playing with a script I made in my PM to test a theory I have about SMF. It did not succeed, so no need to worry. If it did, I would report the security hole (I'm not that much of an asshole).
More information regarding the sample script can be found
here. If for some reason the hole is open, I suggest patch it. This script allows you to steal someone else's session using malformed URL's by exploiting SMF's inability to handle URL's correctly in order to forge a cookie and login as that person.