“There is absolutely no truth to these rumors,” says Cameron Blanchard, SVP of communications for NBCU’s Women & Lifestyle Entertainment Networks–the unit, including the Bravo network, that Zalaznick oversees.

The response from Viacom , MTV’s owner: “There’s no truth to the rumors,” Carole Robinson, EVP of communications for MTV Networks, told me this morning.

How did the rumors spread? They popped yesterday morning on the West coast and moved east like wildfire. Hollywood blogger Nikki Finke fanned the flames with a post saying that Zalaznick is in “advanced talks” to take over Brian Graden’s job as MTV President of Entertainment, heading up MTV and VH1–a job that’s been vacant since June.

Meanwhile, media insiders started believing, since in the wake of General Electric’s just-closed deal to sell 51% of NBCU to Comcast , a key question is: Will the new owner be able to hold on to NBCU’s best talent?

Then there is the fact that Zalaznick had lunch with Spencer Stuart recruiter Jim Citrin at Michael’s, Manhattan midtown cafeteria for the media elite. One media honcho told me that the lunch took place this week–and “you don’t go to Michael’s” with a headhunter unless you want to broadcast that you’re on the market, looking for a new gig.

Alas, the lunch at Michael’s (where I’ve had lunch with both Citrin and Zalanick, separately) took place last week and apparently was an innocent affair. Citrin, who is viewed by some as the media industry’s premiere headhunter, had never met Zalaznick and wanted to get to know her. Simple as that. He is not working for Viacom, at least not now.

As for Zalaznick, she is one of the industry’s most-admired executives because she built Bravo into a buzzy cable network that targets upscale viewers–whom she and her team call “affluencers.” She also oversees NBCU’s Oxygen and iVillage properties. Her clout exceeds the limits of her clumsy title: President of NBC Universal Women & Lifestyle Entertainment Networks. Zalaznick, who is No. 48 on Fortune‘s Most Powerful Women list, created Women@NBCU to market the company’s full lineup of networks–including USA, Syfy, and Telemundo–to female-focused advertisers. NBCU CEO Jeff Zucker, a major Zalaznick fan, also put her in charge of the company’s “Green is Universal” eco-campaign.

Post-merger, Zucker will report to Comcast CEO Brian Roberts. If Zalaznick ends up restless inside the new regime, Viacom would actiually be a natural place for her to go. Her first job in TV was at VH1, which is part of the MTV Network empire. While she was at Viacom, her boss was Jeff Gaspin, now chairman of NBCU Television Entertainment and the guy she reports to.

At MTV Networks, meanwhile, CEO Judy McGrath, a lifer there who ranks No. 20 in Fortune‘s Most Powerful Women rankings, has had a tough slog. Like most other cable behemoths, MTV Networks has healthy margins, but she has struggled to lift ratings and profits and morale since Viacom’s hard-to-please octogenarian chairman, Sumner Redstone, fired her mentor, Tom Freston, from the top job three years ago.

Many people inside MTV Networks, including McGrath, view Zalaznick as a terrific brand builder and have fond memories of working with her. So, consider this: Zalaznick is 46. McGrath is 57. If NBCU proves not to be the ideal home for Zalaznick, she could succeed McGrath…if not soon, someday.