Apparently Robert Fripp is recording the sounds for Windows Vista (link goes to a page with a video). It should be noted that Brian Eno was repsonsible for the Windows 95 chime; one wonders what luminary of seventies English prog rock/ambient Microsoft will tap to make the sounds for their next OS.
Here's hoping it's Patti Labelle... That's a sound I'd like to hear 5,000 times a day.