The Nikon D90 is making waves in the press for supporting movie recording 720p (1280x720) HD video at 24fps. I'm glad we got that out of the way so that we can can go on to talking about the D90 as a useful device.
The Nikon D90 is a DX-format (APS-C) camera with a 12MP CMOS sensor—capturing raw images at 12-bit per-channel—and which has finally received true dust-cleaning support. It also has an increased buffer for burst shooting, and can pull images off its sensor at a fare clip, 4.5fps (compared to 3fps in its predecessor).
The Nikon D90 is the successor to Nikon's D80, and as such it's a very capable entry-level camera. The video functionality, despite its current state primarily as a gimmick, will undoubtedly capture more than a few dilettantes looking to upgrade from point-and-shoots.