Official Episode Description – Episode Stills
 CW Trailer – Clip 01 – Clip 02

Sam and Dean will die in this episode, murdered by Hunters.

Got any Supernatural scoopage? We’re dying out here! —Kristen
Ausiello: That’s just the segue I was looking for! An upcoming episode will be set in heaven — after Sam and Dean have been murdered!
Ask Ausiello

Mose in Idaho: What’s the word on Supernatural? Thanks for all the scoop last week.
No prob. I’m hearing that Sam and Dean will die and go to heaven. Yes, you heard me right. We will see heaven! (Which is funny ’cause I always assumed heaven would look a lot like Jared Padalecki and Jensen Ackles.)
E!Online Spoiler chat

Collin Ford Behind the Scenes picture with Jared Padalecki HERE

Chad Lindberg, who played Ash will be in this episode.
Source and Here

Samantha Smith, who played Mary Winchester will be in this episode.
Source and her Facebook

Traci Dinwiddie, who played Pamela Barnes on season 4 posted in her twitter that she would be in this episode.
Source

Duo the timing, it’s possible that  actor Colin Ford, who played the young Sam Winchester in several episodes will be back for this episode. He posted this in his Twitter:

The 5.16 Episode will be called “Dark Side Of The Moon”

Producers: Jim Michaels, Todd Aronauer
Director: Jeff Woolnough
Shoot Dates: 11th Jan 2010 – 20th Jan 2010

JOSHUA
This benevolent — dignified, very Zen man in his 50’s-70’s is inflappable, simple, but not insincere. A Morgan Freemen type vibe. PLEASE SUBMIT ALL ETHNICITIES. GUEST STAR

Source: SpoilerTV