It has been confirmed! The first ever Double XP Weekend for Call of Duty Black Ops will be starting on February 4th through the 6th, 2011. This is for ALL platforms, not just the Xbox 360, so if you are playing on PS3, PC or Wii, you will be receiving Double XP as well.
It will start at 12PM CST/1PM EST/10AM PST and end Monday morning.
This is the same weekend as Super Bowl 45 as well as the first weekend after the First Strike Map Pack release for the Xbox 360.
Source: MajorNelson’s Podcast from January 30th, 2011