The specs given below for the D7000 are final and pretty much certain. Details on the D4000 & D400 however are a bit less so, but the concept of each of those two cameras, like what each replaces and which sensor it uses, that at least is sure. It is also sure that D5000 was a transitional camera not a beginning of a new series.
D7000
• Replaces D90/D5000.
• Announcement in Jan/Feb 2010.
• 14MP* CMOS sensor (similar to Sony A550 sensor).
• No* AF motor.
• New* AF module: CAM2000, 20 area.
• 5 FPS.
• Live View & 1080* video.
• Articulated 920K LCD.
• OVF same as D90.
• Weight and size below D90 “thanks” to the removal of the AF motor.
D4000
• Replaces D3000/D5000.
• Announcement in 2nd half of 2010.
• 12MP CMOS sensor.
• No AF motor.
• OVF & AF module same as D3000/D5000.
• 3.5 FPS.
• Live View*, but no video.
• Fixed 230K LCD.
• No AEB.
D400
• Replaces D300S.
• Announcement in 1st half of 2011.
• 16MP or higher* CMOS sensor (same new sensor as upcoming Sony A700 replacement).
• AF motor still there.
• 8 FPS (without the grip).
• Live View & special* high quality 1080 video (possibly RAW video???!!!).
• Articulated* 920K LCD.
• OVF & AF module same as D300S.”
D7000
• Replaces D90/D5000.
• Announcement in Jan/Feb 2010.
• 14MP* CMOS sensor (similar to Sony A550 sensor).
• No* AF motor.
• New* AF module: CAM2000, 20 area.
• 5 FPS.
• Live View & 1080* video.
• Articulated 920K LCD.
• OVF same as D90.
• Weight and size below D90 “thanks” to the removal of the AF motor.
D4000
• Replaces D3000/D5000.
• Announcement in 2nd half of 2010.
• 12MP CMOS sensor.
• No AF motor.
• OVF & AF module same as D3000/D5000.
• 3.5 FPS.
• Live View*, but no video.
• Fixed 230K LCD.
• No AEB.
D400
• Replaces D300S.
• Announcement in 1st half of 2011.
• 16MP or higher* CMOS sensor (same new sensor as upcoming Sony A700 replacement).
• AF motor still there.
• 8 FPS (without the grip).
• Live View & special* high quality 1080 video (possibly RAW video???!!!).
• Articulated* 920K LCD.
• OVF & AF module same as D300S.”