Now that we talked about guitar Jams, Lets see what you like in piano jams. Create a list of songs that you think are good!!
Rhapsody in Blue. Or did you mean rock songs? 
Mostly Rock.
see if you can find Dream Theater’s ‘Ytse for Piano’ on napster or something. there’s a piano jam.
Does the long piano solo at the end of “Layla” count?
I hope so. It rules. 
I can’t think of any particular songs without my albums in front of me, but most Ben Folds songs have some cool piano parts in them.
I guess there’s always Jerry Lee Lewis.
Any time Ray Charles is in front of a piano would definitely count here.
Jeez. I knew exactly what I was gonna say and it gets stolen by a couple hours. Oh well. I’ll get you, my pretty, and your little dog, too.
The riffs Billy Preston gets off in “Nothin’ From Nothin’” always appealed to me. Actually, just about anything Preston does appeals to me.
Believe it or not, Paul Schaffer’s piano work on the Blues Bros. “Soul Man” is better than the original Sam & Dave piano work, IMO. In fact, all of Schaffer’s keyboards on that album rock.
If you wanna hear some good piano (not necessarily jammin), check out Joshua Rifkin’s two albums of Scott Joplin’s piano rags. Nonesuch Records. Good stuff.
This is probably stretching the definition of “jam” a bit, but the piano in “Lakeshore Drive” (late 70s [?] song) by Aliotta, Haynes, and Jeremiah is pretty cool.
From what I understand, although “Lakeshore Drive” is about Chicago, it attained a level of popularity in St. Louis that was unmatched in other parts of the country (still gets played a lot), so you may not have heard it.
Yeah, I know…Bruce Hornsby is the Kenny G. of keyboards, commercial as all get out. Still, he has a nice touch.
Roy Bittan-E Street Band
Benmont Tench-the Heartbreakers
No songs in particular and they generally don’t “jam,” just thought I’d mention their names.
Well, not really jams, maybe, but two come to mind.
The piano intro to Van Halens “Right Now”.
The piano fade-out to Dire Straits’ “Tunnel of Love” (pure melancholy).
And Hornsby really IS good.
Keith Jarrett’s Koln (Cologne) concert recording was, I believe, one long jam. Maybe better to call it an improv. Regardless, it’s sensational.