klaymen: See the difference?
pkt-zer0: From a price or content perspective? No, I don't even see how it's relevant.
And I don't see how announcing the expansions in advance is a bad thing, either. Not keeping customers in the dark about their plans is a good thing, as far as I'm concerned (refer to: L4D2).
One thing is announcing expansions in advance, but splitting the game into three parts because some manager wants to buy new Porsche for his grandma is like saying: "We will charge you for this, because we can."
What will be next? Announcing SC2 expansion a year after releasing all three SC2 campaigns and saying that it will be again released in three parts?
Starcraft has hordes of fans, Blizzard knows it.
And Blizz knows that he can milk them, because fans (and fanatical fanboys) will buy all 3 parts and maybe the final collection (all 3 parts together) too, if there will be any, just for the sake of Starcraft.
From marketing perspective it is understandable. But treating your fans as a milk cows just because you can....