Nikon just announced the D3x, and popped out the D700 a little bit ago, so next to be updated is the D300, right? Here are the first round of supposed specs for the D400.
Nikon Rumors got these specs as anonymous tip—anonymous comment, actually—so the standard caveats apply, BUT they do look fairly plausible, and fall in line with what Nikon's been up to lately. The most significant update is the addition of the rumored 1080p 24fps video recording, a whack back at Canon's 5D Mark II, whose video capabilities have blown us away again and again. Of course, we'll have to wait and see how good it actually looks. (Here's why DSLR video is finally happening, if you're curious.)
The rest is fairly expectable with a mix of current Nikon features and new specs—14.8MP DX sensor, but I'm hoping it'll be more D700-like in the noise department—and $2000 seems about right as the price tag, though $1800 would be more aggressive.
* New 14.8 megapixel DX format CMOS sensor effective 14.3 megapixel
* Self-cleaning sensor unit (low-pass filter vibration)
* ISO 100 - 6400 (with boost up to ISO 25600 and down to ISO 50)
* 14-bit A/D conversion
* Movie capture at up to 1080p 24 fps with stereo sound
* Nikon EXPEED Plus image processor 30% faster than previous EXPEED image processor
* Super fast operation (power-up 13 ms, shutter lag 40 ms, black-out 90 ! ms)
* Kevlar / carbon fibre composite shutter with 200,000 exposure durability
* Multi-CAM3500DX Auto Focus sensor (51-point, 15 cross-type, more vertical coverage)
* Auto-focus tracking by color (using information from 1005-pixel AE sensor)
* Auto-focus calibration (fine-tuning) now available (fixed body or up to 20 separate lens settings)
* Vignetting control in-camera
* Automatic chromatic aberration correction
* Custom image parameters now support brightness as well as contrast
* Seven frames per second continuous shooting (nine frames per second with battery pack)
* 3.0″ 922,000 pixel LCD monitor
* Live View with either phase detect (mirror up/down) or contrast-detect AF, face detection
* 'Active D-Lighting' (adjusts metering as well as applying D-Lighting curve)
* Detailed 'Control Panel' type display on LCD monitor, changes color in darkness
* Buttons sealed against moisture
* Same ultra-fast startup and shutter lag as D700
* Scene Recognition System (uses AE sensor, AF sensor)
* Picture Control image parameter presets
* UDMA compatible single CF card slot
* Virtual horizon indicates if camera is level (like an aircraft cockpit display)
* Extensive in-camera retouching
* HDMI HD video output
* Magnesium alloy body with connections and buttons sealed against moisture
[Nikon Rumors via CrunchGear]