Microsoft’s Xbox Live online gaming service launched today its latest exclusive, the Escalation map pack expansion for multiplayer gaming in Call of Duty Black Ops.

Activision Blizzard’s latest map pack is the second release of downloadable game content for Black Ops. And as past map sales have proven, this launch will likely generate as much revenue as a new blockbuster game launch on the consoles.

Right now, there are 333,316 players online. That’s about three times as many as I saw last night. That’s not a huge number, but it’s a given that today is not a great day to launch a rival game. At the moment, there’s nothing in the game that resembles the attack on Osama bin Laden’s complex in Pakistan. But you have to figure that’s going to be on the minds of gamers as they play this kind of intense, first-person shooter game.

Given the timing, Microsoft’s Xbox Live is going to be a big beneficiary of the map pack release. Meanwhile, Sony is suffering two major outages because hackers attacked its PlayStation Network and PC online gaming services.

Activision Blizzard has said users have played the Black Ops game online for more than 2 billion hours since its launch in November. You can expect more Call of Duty fans to log into the Xbox Live service starting today, since they won’t be able to play on the PSN or on Sony Online Entertainment’s PC online games, which were shut down today pending an intrusion investigation.

I’ve actually put 60 hours into the multiplayer combat version of the game, which is second to none, in my opinion. I’m at the equivalent of level 89 (since you can get up to level 50 and then start over again). I picked it up again last night to get back in the swing in preparation for the Escalation launch. Activision Blizzard has timed this launch of new content well, as it will bring back players who have stopped playing the game.

The new map pack will have five maps, entitled Zoo, Hotel, Convoy, Stockpile, and the zombie map Survive. The price wasn’t listed, but previous map pack First Strike was sold on Xbox Live for 1200 Microsoft Points, or $15. (See the smack talk from EA’s chief executive about Call of Duty). First Strike sold more than 1.4 million copies on Xbox Live on its first day of sales.

Call of Duty Black Ops is one of the best-selling video games of all time, with sales of more than $1 billion since the launch in November. Activision Blizzard previously launched its First Strike map pack in February.

Activision Blizzard said some time ago that it had sold more than 20 million Call of Duty map packs, generating more than $300 million in sales. So it’s clear that map packs are a big business, and video game publishers may want to avoid publishing rival games on May 3, since gamers will be a little busy.

On the weekend of May 6, Black Ops players can earn double the amount of experience points in each match they play. Check out the funny trailer below, which cleverly says “there’s a soldier in all of us.”