Canon USA, Canon UK and Canon Inc have announced that the Canon EOS-1D X will be available in late April. Here is Canon USA's announcement:
Updated Availability for the EOS-1D X DSLR Camera and Accessories
We would like to inform you of an update to the expected availability of the EOS-1D X DSLR Camera and its optional accessories, the WFT-E6A Wireless File Transmitter and GP-E1 GPS Receiver. The camera and accessories are now anticipated to be available at the end of April 2012. We apologize for any inconvenience this delay may cause.
Additional Canon EOS-1D X Specs
Canon Inc has filled in some of the TBA specs:
Weight: approx. 1340 grams for body; approx. 1530 grams with CIPA Camera & Imaging Products Association standards
Possible Number of Shots (CIPA Camera & Imaging Products Association standards):
View Finder shooting at 73°F/23°C Approx. 1120 shots
View Finder shooting at 32°F/0°C Approx. 860 shots
Live View shooting at 73°F/23°C Approx. 290 shots
Live View shooting at 32°F/0°C Approx. 250 shots
Here are the official announcement pages:
Canon Inc.
Canon Inc. b
Canon UK (a more-verbose press release)
Canon USA
(thanks David & Kaz)