Probably the most awesome raids for me were the ones which involved Old Gods. There was nothing more cool/unusual than seeing a giant thousand mouthed octopus which could mind control you!
I have seen some of the new Cata content and it looks like the Old Gods will at the least play a large role in the content ... if not actually appear in raids.
The question is; how many/what kinds of Old Gods would you like to see or fight in a dungeon? "After 4.1 to be precise "
There is no way you will fight more than one old god in a single raid. It is possible that we will see one in Cata in a raid, but we dont know yet.
I would like very much to see them in raids, and it would be cool to see a old god who has some control over time (im not saying one does, but it would be a fun encounter at least)