from the nikon press release:
For the first time in digital SLR photography, Nikon introduces the addition of the D-Movie mode, allowing consumers to create their own HD movie clips (1280 x 720) with sound from their D-SLR camera. Photographers will appreciate the cinematic qualities that come from the 24fps frame rate, which matches theatrical film, whether producing vacation clips or creatively melding stills with video. Additionally, the large size of the D90’s DX-format sensor, combined with the optical superiority and broad selection of NIKKOR lenses, provides shooters with the ability to capture amazing perspectives not possible with typical camcorders. D-Movie clips also benefit from Nikon VR image stabilization, which is automatically activated during recording to aid the low-light capability that trumps many other hybrid devices. Users can record movie clips onto an inserted SD / SDHC card, created as Motion JPEG AVI files that are easily edited with widely available video editing software. The D90 also features an HDMI terminal, allowing viewing of both pictures and movies on High Definition televisions.