There's no two ways about it: we're excited about the LEGO Mindstorms NXT. We've wrestled the Transterpreter onto the Mindstorms, and will be using it in the classroom this semester as part of the University of Kent's module on concurrent and parallel programming (how cool is that!). However, the NXT looks like it will offer some really excellent features, including Bluetooth communications, serial connections for sensors (or any other device), and what looks like some nice additions to the motors.
I would love to be part of their developer program over the next few months. I submit my dissertation shortly, and have dreamed about having time to develop course materials surrounding the LEGO Mindstorms and the Transterpreter. So, LEGO, if you're listening: we've got a team of six people out here working on the Transterpreter, plus many more on Kent's faculty involved in the First LEGO League in the SouthEast of the UK, and we'd love to take part in the developer program!