A little disillusionment and insight. My dad is one of the beta testers, so I've been staring at the brick since February.
The NXT software is a little buggy in terms of block placement and "beam" (execution flow) handling (at least in my version). It's based on Flash and LabVIEW. (Which, in turn, is based on Gecko/Mozilla. Don't believe me? Compare the DLLs in LabVIEW to Firefox.) One of the cooler features is the ability to "wire" parameters from one block to another, so not every piece of data has to be stored in a variable. This is also used to allow you to add arguments to user blocks. There's also the ability to comment programs. Big help for long ones.
The NXT itself has ports for 3 motors and 4 sensors, one of which is "IEC 61158 Type 4/EN 50 170 compliant". (Translation?) The ports are the same size as phone cables, but with 6 leads and the clip off to one side; mirror images of 6-pin DEC/MMJ connectors.
The NXT software allows access to virtually every function, including Bluetooth, buttons, display, "files", sound, on and on. One of the sample images looks like Atari's Super Breakout. (I'm waiting for someone to make it.)
This is an upgrade comparable to the PBASIC/PIC18 upgrade back in 2004.