In past model years there has sometimes been a laundry list of changes from when the snowmobile media first sees the new releases to the time the model goes to production.
Not so for the 2011 mountain models. You could fit the changes on a Post-It note.
The only change from any of the Big Four comes from Ski-Doo on its Summit Everest model. BRP is discontinuing blue as a color option on the Everest. It is now only available in black. So disregard any of those pictures where you might have seen an 2011 Everest model in blue.