With season 4 less than two weeks away, we assembled some info on it. Please understand that this info is not necessarily 100% correct.
As noted before, season 4 is scheduled for a Dec. 9th premiere at its usual sunday time slot (7PM/6PM Central/Mountain). The episode to air as a premiere is going to be "Roswell that Ends Well", previously known as "Top Secret Season Premiere Extravaganza" and written by J. Stewart Burns (The Cryonic Woman, Mars University and others).
Short premiere synopsis: "An accident causes a supernova which sends the crew back in time to 1947, where they land in Roswell, Area 51. Fry and Bender's head have to go in for a rescue mission to free Dr Zoidberg and Bender's body from an army base where Fry's grandfather works."
It really is an episode done in the season 3 production run.
Quite some other Season 3 episodes have yet to air. Partly preliminary titles and summaries are (skip paragraph if you don't like to read spoilers):
3ACV10 - Where the Buggalo Roam: Amy and Kif save the Buggalo herd of the Wong family from rustlers
3ACV12 - The Route of All Evil: Cubert and Hermes' son Dwight use the Planet Express crew to help with their paper route.
3ACV16 - A Leela of her own: Leela starts playing Blernsball as a pro
3ACV17 - A Pharaoh to Remember: Leela, Fry and Bender become enslaved on a planet which resembles the ancient Egypts
3ACV18 - Anthology of Interest II: 3 What ifs: Bender as a human, Fry in a Video game and Leela goes home.
3ACV03 - A Tale of Two Santas: The episode not shown due to violence. It is scheduled to air Dec. 23rd at between 9 and 10PM together with the first XMAS episode. Possibly a guest star: Coolio.
3ACV20 - Godfellas: Bender gets rocketed into space and meets god
3ACV21 - Future Stock: Something weird happens on the annual share holder meeting
3ACV22 - Ironic Chef: Bender tries to beat Elzar at a cooking marathon
Some spoilers for the real season 4 episodes:
The episode currently scheduled for the season final will be about the cult of Star Trek that grew into its own religion around the 23rd Century and became too powerful in the coming centuries and thus got banned . Possibly featuring: William Shatner, Leonard Nimoy, George Takei, Walter Koenig, and Nichelle Nichols as voice guest stars.
A Valentines episode is to guest star Sigourney Weaver as the voice of the PE ship (it gets a personality upgrade which Bender grows quite fond of).
Together with the 18 episodes out of the 4th production run a total of 72 episodes will have been produced. It is not that clear how many are actually going to show during Season 4 due to lots of football.
OK, that's it for now, warm up your video tapes and buy chips already ;)