The debut will be streamed on the site starting Oct. 23, as well as on sister site Hulu.com, before it launches on the network on Oct. 30 (Thursday) at 9:30 p.m. NBC said Monday that Salma Hayek will become a recurring guest star on the show as a love interest of Alec Baldwin's character Jack Donaghy.

The comedy has been sort of a "big-niche" hit over the last two years--but may get added kick, thanks to the sensation of Tina Fey's Palin impersonations on "Saturday Night Live." (They also gave the show a boost in ratings.)

It's unclear whether the special advance screening will have a dedicated sponsor or NBC.com and Hulu.com will simply run pre- and mid-rolls from current advertisers. "30 Rock" is entering its third season, and episodes from season two are available on both sites.

NBC is banking on "The Office" at 9 p.m. delivering viewers to "30 Rock," which follows. For the first two "Office" episodes this season, "live-plus-same-day" ratings in the 18-to-49 demo grew slightly from episode one (which was a full hour) to two.

"The Office," however, loses some potential pop as a lead-in because it is one of television's most-watched shows in delayed fashion, via DVRs. The first episode this season posted a viewership gain of 18% when comparing with the "live-plus-same-day" 18-to-49 rating (4.9)--the go-forward figure for "live-plus-seven-day" is 5.8.

Last year, "30 Rock" at 9:30 p.m. followed "The Office" three times and retained on average 69% of its audience in the 18-to-49 demo.

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