I've got a weird one. I've got all of my guys running on a BES here, and this morning some random BIS account popped up one of their 8830's. He hasn't set one up, doesn't know where it came from or the e-mail address associated with it, and Verizon doesn't see the account created in their BIS admin console (or anything associated with his PIN). Has anyone seen anything like this before?

I'm not so sure I'd take the user's word for it.
Are you sure the user didn't try to set up their own BIS account, and are now playing dumb about it?
In my experience in IT... users lie.

Yeah, I definitely agree on that one

Got up with tier 2 support at Verizon and they said that the BIS address was associated with another PIN, had me delete the service books for that account and re-register the device on the network and all seems to be fixed. They said they'd never seen it before either, but that there definitely wasn't a BIS account associated with this guy's PIN. Thanks!

Verizon is in a position not to see the BIS account if it were deleted. If the service books were on there, it was either an issue where the user created a BIS account and lied, or a BIS account was setup for the user by mistake but was later removed at Verizon or RIM. When it was removed, the service books remained until deleted.