As title updates go, this ranks as a very minor tweak. However, we all like to know what's being applied to the game behind the scenes, mostly because we're nosey.
This update (the eleventh applied to the title so far), addresses a number of 'unidentified security' issues, and audio tweaks. The audio alterations are specifically aimed at fixing the problem when planting/defusing a bomb in Search and Destroy.
The update will, as ever, be detected when you next fire up Call of Duty: Black Ops
and clocks in at a tiny 14MB.