There are no solid details on the next Palm Pre device, except that it will run the new WebOS and be smaller than the upcoming Palm Pre. Rumors indicate it could be out before the end of 2009.
I think offering a couple of slightly different form factor options may appeal to a wider audience and help Palm as they try to stay afloat in the mobile space. If the on-screen keyboard is decent, then going with a more compact and more pocketable device may make even more sense than the current Palm Pre.