Some folks over at the Call of Duty Forums have been checking out the Activision servers and found the image below at http://www.callofduty.com/bo2/images
It appears to include the date for a possible reveal, maybe we shall be seeing the first Black Ops 2 trailer on the 28th April. The 28th April was when we saw the first trailer for Black Ops exactly 2 years previously. Or possibly Activision may just confirm that the game is in the works on this date?
It does look as though this could be legitimate, and was removed as soon as it was discovered, or of course it could be a very well thought out hoax.
If it is real we could be expecting to see the first trailer for Black Ops 2 later this month!