Watch with Kristin

Edward Opinaldo, PacificCoastNews.com

It's true!

Inside sources have confirmed that Leighton Meester and Blake Lively will be guest starring on NBC's 30 Rock this season, playing former high school acquaintances of Tina Fey's character, Liz Lemon, in what is currently slated to be the fourth episode and will air in November.

Insiders are spilling exclusive details of how it went down and what they'll play...

As first reported by my dear frienemy Michael Ausiello at EW.com, the Gossip Girl starlets have signed a deal to appear, but Gossip sources whispered to me late last week that 30 Rock had actually been trying to get more than Meester and Lively to appear. "They originally wanted to have all the main Gossip castmembers appear as a group in a scene with Tina, but it's been tricky to work out with the shooting schedules."

"We want to make it work with 30 Rock," a Gossip insider told me on Monday. "They shoot across the hall from us."

Not to mention, executive producer extraordinaire Josh Schwartz works for both the CW, helming the rich and beautiful Upper East Siders, and also for NBC, helming Chuck—which, I'm told, helped to bridge the gap between the two networks in order to make the deal with Blake and Leighton go through.

According to sources, in the episode, Jack (Alec Baldwin) will get stuck (via snowstorm) going with Liz to her 20-year high school reunion at White Haven High in Philadelphia. She tells Jack she was a big nerd in high school, but in flashback scenes (which will include Leighton and Blake), we'll see she was actually always hurting people's feelings.

Oh, and contrary to the photos above, Liz Lemon did not go to school in the 1800s (those photos were taken on the G.G. set). The girls will be looking very '80s in the flashbacks.

So just to tally all this up, we now have Will Arnett, Jennifer Aniston, Oprah (not yet official but looks like it will happen) and the Gossip girls, all appearing in the first few episodes of the season. Somebody's got friends in high places! 

What do you think of all these guest stars? And anyone else hoping Fey will have a good ol' catfight with Queen B?