Windows Mobile 6.5: Due October, pretty much as is. Windows Mobile 7: Coming at the end of next year. Both: On sale at the same time, marketed in a bizarre two-tiered way. If this rumor isn't false, it should be.
Mary Jo Foley has a twofer on the new Embedded Compact core of Windows Mobile: Cashmere, if released, would add FlashLite and better gesture support, while Alchemy is a new shell component that would bring "richer UI scenarios" through native access to Silverlight, meaning flicking, panning and zoomzooming.