No, none of the DLSRs (Nikon, Canon, Sony, Panasonic, etc) are 4:2:2. The one exception being a GH1 with the hack and MJPEG 4:2:2 settings.
In fact the lowest price cameras that I know of (new) to offer 4:2:2 (on camera) are the Canon XF100 ($2995) and the HVX200A ($3195)
I'm willing to bet though that the 5dMK3 goes to the MXF 4:2:2 codec...and not because of the rumor mill...but because it makes logical sense for Canon to do so. a.The 5DMK3 is too important camera for them to adhere to the current codec b. MXF already records to CF cards. c. Canon's known for migrating features AFTER they've been tested by the marketplace.
Their 3 year VDLSR evolution has been pretty much a linear process:
5DMK2- people fell in love with the video but wanted true 24P and more recording options...
The 7D gets it all off the bat
The T2i gets it all as well for less money -but people wanted audio control and better way to monitor the video
The 60D gets all the above plus an articulating screen and manual audio
The T3i gets all the above plus a 3x to 10x zoom feature for less.
END OF 3 YEAR CYCLE (I know I left things out like firmware updates, and in between ISOs, etc.)
The 5DMK3 will be the jumping off point for their next 3 YEAR CYCLE, so in my mind a new codec (hopefully DIGIC V brings new process of getting 1080P) is on the way.
Sorry...I posted to answer the question and went off on a tangent.