It's one thing to do the occasional talk show appearance or Saturday Night Live gig.

But as Jay Leno reveals that NBC News anchor Brian Williams is among the regular cast of comics and entertainers who will populate his 10 p.m. program The Jay Leno Show this fall, you have to ask:

Is NBC risking the network news anchor's credibility to prop up its prime time gamble?

Certainly, Williams has pushed the envelope in terms of blending the news anchor job with entertaining. Armed with a quick wit and easy appreciation for comedy, the anchor has already broken barriers by hosting SNL (a first for a sitting network news anchor) and making regular appearances on The Daily Show with pal Jon Stewart.

But joining a regular, rotating crew of comics -- which will also include D.L. Hughley, Mikey Day, Rachael Harris, Jim Norton and the Dan Band -- is a new venture, even for a news anchor who has actually done stand-up at New York's Upright Citizens Brigade theater.

Leno announced the move in Los Angeles at the TV critics' summer press tour, where news reports noted he's running 4 miles a day, has lost 12 pounds and plans a show that's light on guests and desk-bound comedy bits, to try and build differences between his show and Tonight Show successor Conan O'Brien.

It all sounded like Leno's trademark mix of self-deprecation and dogged determination -- which opponents have found to be a deadly combination. “If we go down in flames,” Leno said, according to the New York Times, “we’ll be laughing all the way down."

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