The Palm Pre is going on sale on June 6th, but another Palm phone is already making headlines again.
In early May the thin Palm Eos emerged as rumor. Engadget published an AT&T slide showing the details of the Palm Eos. The Eos is scheduled for a second half of 2009 release and would have a $349 rather high price tag even with the $50 Mail in Rebate listed.
The Palm Eos measures 55x111x10.6mm and weighs just 100g.
Features of the Palm Eos include 2.63 inch touch screen with 320x400px resolution, 4GB storage, HSDPA, 2MP camera and A-GPS.
I would be surprised if the Palm Eos is not running the new Web OS, but it does not say explicitely on the slide.

At 10.6mm the Palm Eos is thin, but I do not see this being a reason to wait for it. If you want a new Palm smartphone go for the Palm Pre.