Brighthand has an article with a list of updates rumoured to be on the new Pocket PC 2003 OS, not yet released.
The list includes OS support for Bluetooth and Wi-Fi, better Pocket Internet Explorer with Javascript (not Java) CSS and XHTML support and Windows Media Player 9.
One of the important things is the fact that it should fit any device with 32MB ROM or more. Great for people expecting this on current products!