Attendees at PaleyFest 2010’s Glee event got a number of juicy spoilers concerning the show’s remaining episodes.

What musical moments can fans look forward to when the program returns on April 13? A Madonna-themed episode, duets with Neil Patrick Harris…and even a Lady Gaga cover.

“She’s arguably the most important pop star right now,” co-creator Ryan Murphy said about the “Bad Romance” singer. The unnamed tune will appropriately be featured in an episode about the “power of theatricality.” (Let’s hope lesbian prison porn is not included.)

“I started rehearsing this dance in December and we did it almost a day,” Jane Lynch (Sue Sylvester) revealed about her upcoming Madonna performance. “We filmed it with the video (for ‘Vogue’) playing in front of us as we shot it and paused with every movement.”

Meanwhile, Matthew Morrison (Will) gave us a clue as to what he’ll be singing with an old high school rival (Harris). “He’s on the school board and trying to take down the glee club. We have two duets, Aerosmith and Billy Joel.” That episode will air sometime in May.

Looking even further ahead, the producers have already announced something new they have in store. “We are going to do an episode in the second season with all original music,” Murphy stated. Considering FOX will likely air 25 instead of 22 episodes next year, a few original tunes couldn’t hurt.