NBC Universal has officially locked up more than $1 billion in advertising sales for the Olympics — and says it has more to sell as the games begin on Friday.

The media company majority-owned by General Electric has said all along that it was aiming for sales in excess of $1 billion, and has trumpeted the 3,600 hours of coverage it is running across the NBC network, cable channels, and online sites.

By some estimates, 30-second TV spots have been going for around $750,000, showing that live events are commanding top dollar from advertisers because they represent one of the few programming choices that consistently draw mass audiences. Moreover, viewers tend to watch such broadcasts in real time, rather than on digital video recording devices that allow viewers to skip through commercials.

Oh yeah, presidential candidates John McCain and Barack Obama have bought spots, too, undoubtedly for the same reasons.

That’s all very good news for NBC Universal, which can take the first victory lap of the games.

But there is more to consider looking out over the next couple of weeks. Namely, are the ratings going to justify all this spending? After all, since the last summer Olympics, media choices have only expanded. The same movement to online that NBC is trying to take advantage of, with its streaming web video, is the very thing that could hurt its ratings.

What about the potential for violence? Protests? Marketers have largely stuck to the argument that the Olympics are a showcase for athletes and they aren’t concerned about the politics — but are any of them going to be all that happy if commercials end up running against a backdrop of violence?

We’ll see how this plays out.

(Photo: Reuters)