I was just reading the PCGamer magazine, and without spoiling anything else, it seems like you can actually join the Imperial Legion. I don't know if it's like a separate faction and questline like Morrowind, but I haven't seen any other topics so there you go.

it was confirmed a while ago that you can join either the Stromcloaks (Rebels) or Imperials & advance in rank.

The real question is to what rank we will get, i would love to have a squad of soldiers i could have as companions.

Amen to that! Advancing to an imperial officer rank or equivalent and command other NPCs would be great. This should have been in Oblivion already.

Its been confirmed for a while that you can Join the Imperial Legion and the Stormcloaks, plus a few other small factions!! Bethesda has really stepped it up!

Alright thanks for the clarification, I just hope it's not like in Oblivion where you "join" the Blades, but there is no actual questline for the faction except for the main quest itself. I really hope it has it's own questline and epic ending, like the Dark Brotherhood!

Its separate than the main quest so don'tcha fret.