--Went to a gathering last night and a pal brought along a bot he'd cobbled together from the new Lego Mindstorms kit. It had a line sensor, an accoustic sensor, an infrared sensor and a microwave sensor on it, plus he'd added Ackerman steering. It sensed a line (big fat line maybe 3/4" wide on a fold-out that made an oval track for the bot to follow) and followed it very well, with sensor on a rotating fixture doing a rapid side-to-side scan no more than 1/4" to keep vehicle aligned. Wheels tracked true; very nice. All cabling appears to connect with modified telephone jack-like devices and there's a USB port in the onboard controller. The really neat thing is that it needn't be connected via USB to be programmed, as it's got Bluetooth. In addition to this it's possible to program the thing directly, using the four or five buttons on the controller to navigate a series of menus. My pal also brought along a nifty printout that can be made to display the path and the programming steps it took to make it, in a graphical, rather than text format: very neat.
--Having just laid out cash for the Vex stuff on sale I'm kinda priced out of the market for a while, but this second iteration looks like a real improvement over the first Mindstorms.