The Treocentral forums are the best place to find out about upcoming Treo smartphones. As you can see by the pdf posted at Treocentral, it's from "The Sprint Retail Sales Playbook".

"The fourth page of the playbook shows the launch calendar for the next 4 weeks. Usually pretty boring stuff, but of note is that Sprint has now officially announced the release date of the Treo 700p to be on May 28th. This coincides with a lot of the speculation of the release date that I've seen. Also launching that day in Sprint retail stores is the Blackberry 7130i and the LX550 by LG."

So it looks like the Treo 700p will be launched May 28, 2006 so start saving now:) I know I am:)