According to an image released by The Phone House, a retailer in The Netherlands, the new Treo smartphone that is being officially launched in Europe this Wednesday will be called Treo 500.

Although the model number suggests a several year fall back in functionality to days prior to the Treo 600, rumored specifications indicate otherwise. The Treo 500 is expected to have a 2 megapixel camera, 240×320 screen, 150 megabytes of memory and 3G wireless data connectivity.

The Treo 500 is expected to run Windows Mobile 6 Standard Edition and have a MicroSD expansion slot. Like many competing models, such as Blackjack, Sidekick, Dash and Q, the device may not have a touchscreen. There are conflicting reports as to whether it will pack UMTS.

These substantial hardware improvements are being jammed into a tiny form factor. At 16mm, the Treo 500 is said to be 6mm (or about 25%) thinner than the Treo 750, the smallest Treo smartphone currently in production. The other dimensions are 61mm wide and 110mm tall.

More to come when Palm releases the device this week!