T-Mobile quietly released information about the upcoming MDA III on its website. It's an upgrade to the MDA II, and adds features like WiFi and a slide down thumb board. Here are some of the other features:
In Germany, the MDA II has a 40% market share of "PDA Phone" sales. Look for the MDA III in September. This phone is not scheduled to come to the US market, but you will be able to import it like the MDA II.