This is strictly a second-hand piece of information from a Verizon retail salesman. I've known this guy for awhile and he's generally accurate with upcoming products. Take this for what it's worth:

He tells me that the Verizon Treo will be smaller than the current version offered by Sprint, Tmobile, etc. He said the regional sales managers are running around with these units already, 'testing' them prior to release on their network.

Given we haven't seen any FCC leaks on a newly designed Treo, I'd doubt this to the case, but you never know. It could also mean there's a competing PDA/phone combo on deck for a Verizon release.