I would rate this rumor @ 1% probability. Nikon D3xs specs:
- 24 MP ISO-100 to 3200 with Lo-1, Lo-2, Hi-1, Hi-2
- 5 fps. (12-bit), 3 fps. (14-bit), 9 fps (High-speed crop), 1 fps (16-bit)
- New NEF Metering mode and JPEG Metering mode
- Full HD with RAW mode
- Available in June 2010 after Canon 1Ds Mark IV
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