The Purple Piano Project (3x01)

The episode is titled "The Purple Piano Project" and will involve Blaine transferring to McKinley.

Who is graduating and who is staying will be revealed in the first few minutes of this episode.

A school musical plotline will begin in this episode.

Two new characters will be introduced, Sheila (unknown yet who's playing this character) and Sugar (played by Vanessa Lengies)

Within the first 2 pages of the script, Rachel gets slushied.

Santana is back on the Cheerios.

Brittany is back on the cheerios.

Mike's parents have a different idea about what he should be doing with his life

Kurt and Blaine will not be breaking up but there will be some competition between them Source (This is a spoiler for them during the season)

The winner of the Glee Project will be introduced in this episode and will audition for New Directions in a new and unusual way. However, the winner won't be on set until the reality show ends, which is August 21st.

Kurt spends most of the episode trying to make Blaine transfer to McKinley.

A Mike/Tina storyline will begin this episode. Mike is a senior while Tina is a junior which will cause problems for the couple.

Quinn's Storyline

Quinn is going 'bad girl'. Source This involves a completely new wardrobe that is unlike anything she has ever worn before. Source Furthermore, Dianna Agron has been spotted with new dyed pink hair. Source
Iqbal confirmed that this is part of Quinn's new storyline.

Quinn's new wardrobe involves an upside down cross.

It also involves a shirt that says "Hell is so hot right now". Quinn is also not wearing her cross that she clung to throughout series 1 and 2.

Scenes

Blaine and Kurt have a scene at the Lima Bean.
Quinn and Rachel have a scene together.

Will, Emma and Beiste have a scene together.

Sue has a scene where she tries to remove a purple piano from a room - citing how it looks like Liberace died on it.

Mike and Tina have a scene together.

Kurt and Rachel have a scene together in Emma's office.

Josh Sussman (Jacob Ben Israel) will be in this episode.

Tina, Mike, and Artie have a scene together.

Mercedes has a scene with a new costar. Since this was posted before the end of TGP, it is more likely the costar is her romantic interest, not the TGP winner.

Lea tweeted that she got to see Darren perform and because they attend different schools, this suggests Blaine will be attending McKinley and possibly auditioning for ND.

There will be a number involving the characters tap dancing.

Blaine sings "It's Not Unusual" with The Cheerios in the Mckinley courtyard. Blaine has lead vocals and is not wearing the Dalton Academy Uniform. The rest of ND is there, but apparently they are on the fringes watching, not participating. Darren wears a red shirt and highwater jeans. Lea and Chris are “kind of” in it (Lea is sort of “running around like she’s in a French movie” and Darren does some cheesy wink/thumbs up to Chris during the song). Quinn is with another group, smoking and watching the performance. At the end of it she flicks her cigarette at the piano and the piano goes up in flames.

Lea and Jenna tweeted they filmed the finale number for this episode. They both described this number has a lot of dancing and Lea said it's a super fun song.

The first number of this episode: "Dancing Cheerios and Exploding Pianos" Source The preparation of Season 3 began on August 8th, such as dance rehearsals, recording the songs and warbrobe fittings.

Rachel and Finn have officially kissed.

Santana is made captain of the Cheerios, but she’s a little bent out of shape when Sue informs her that she’s got a co-captain — and that person’s not too keen on sharing either. Source In 'Funeral' Sue said that Becky would captain the Cheerio's, meaning it is most likely her.

Jacob will be in the first episode. He said that he's not doing anything creepy.

Production

Eric Stoltz is directing this episode

Filming began on August 9th. Confirmed by Dante Di Loreto (One of the executive producers of Glee) Source The first episode features a lot of songs that aren't in the charts but were hits in the past.

Music

Rachel (Lea Michele) has some great stuff with Blaine (Darren Criss). Source
The following cast members have been confirmed to have been in the recording studio: (This does not mean those unlisted have not been)

Lea (3 songs)
Cory
Amber
Chris
Naya
Mark
Heather
Darren

Other

Adam Anders confirmed he does not know if Harry will sing in this season yet Source
This episode will air on Tuesday, September 20th at 8pm.

Max Adler (David Karofsky) may not be in the first episode due to his movie filming, which ends August 12th.

Songs

At the moment, it is unknown when the actors were recording in the studio, if it was a solo, in a group number/duet or a song to themselves. Ryan said he wanted to keep it to 4 numbers an episode.

It's Not Unusual by Tom Jones. Sung by Blaine with the Cheerios.
Parachute by Cheryl Cole. Sung by TBA
TBA by TBA. Sung by Rachel.
TBA by TBA. Sung by Finn.
TBA by TBA. Sung by Mercedes.
TBA by TBA. Sung by Kurt.
TBA by TBA. Sung by TGP Winner.

Guest Stars

Ashley Fink as Lauren Zizes.
Dot Jones as Shannon Beiste.
Josh Sussman as Jacob Ben Israel.
Vanessa Lengies as Sugar.
TBA as Sheila.
LaMarcus Tinker as Marcus.
The Glee Project Winner as TBA.