At Microsoft's Techfest, a researcher was showing off a smart shuffle system that uses tags and meta data like tempo and genre to direct playlist creation in a portable music device. The demo was being done on a first generation Zune.
The system is being developed in direct response to the huge number of songs people carry around on their media players, and specifically the millions of songs a Zune library can stock using a Zune pass. The system automatically recommends new songs based on songs played, and the logic is continuously "steered" by voting tracks up and down.