They appear to be unsubstantiated, but since we specialize in unsubstantiated rumors around here, consider this speculation, from a guy who calls himself
stockoperator_1999:
Sprint retail outlets will be receiving the 700W on Friday May 12th for a Monday May 15th launch. No final confirmation on the 700P yet. (Launch date or carrier)... The odds are looking like Verizon will get the 700P first around the same time Sprint gets the 700W. (Sprint will get it also, it's just a matter of when... I'm hearing May 28th, which is 2 weeks after the espected Verizon launch.
Related: Sprint Treo 700w expected to arrive earlier