If you were in the market to replace a phone, PDA, GPS and camera, then I would have suggested the soon to be released iPaq phone for "synergy."
Has GPS, but not wi-fi (hey, it's a phone!) The HP device will feature GSM/GPRS with EDGE mobile phone connectivity, plus Bluetooth and GPS satellite positioning. The unit appears to have both a Mini SD and a SD IO slot, a 1200mAh battery, and the inclusion, on the rear of the device, of a 1.3 megapixel digicam. Powered by a 520MHz an Intel XScale PXA270, running Windows Mobile 2003 Second Edition.
The screen is roughly 3.2in 240 x 240 pxl, smaller than the Treo 650's 320 x 320 unit. The phone is roughly the same size as the new PalmOne 650 but wider but there's no antenna stub and no fold-out receiver for the GPS system.