From the Call of Duty:Black Ops Intel Page:
The official Call of Duty: Black Ops trailer has arrived! This extended 90 second trailer is available first, exclusively on Black Ops, and is comprised entirely of in-game footage. It should set the scene we at Treyarch intend to capture this year with Black Ops.
One other little tidbit of information is that the callofduty.com domain name is now forwarding directly to callofduty.com/blackops so there is no more home page selection screen to go to the title of choice.