I saw in an interview that they've been working on SC2 since WC3: The Frozen Throne was released. They said they wanted to announce a game that was playable for once. So maybe 2009 is too far away?
They will always be dragoons to me. Immortals... pfft. This isn't underworld, blzzard!
The SC2 site explained that the buildings that produced Dragoons were destroyed by the zerg, along with the plans for them, hence the creation of the Immortals.
The game looks like it'll be fun, but I have trouble playing RTS competitively. I just simply can't track that many things at once.
STory I read said that the Immortals are just upgraded Dragoons.
I'll warn of a spoiler if someone wanted to actually find this out via the game when it comes out, but this comes directly off the Starcraft 2 website.
Starcraft said:
Before the loss of Aiur, veteran protoss warriors who had been crippled in battle could volunteer to continue their service by being transplanted into dragoon exoskeletons. Now, the dragoons of the past are all but gone. The sacred shrine that was dedicated to the creation of the dragoons was infested by the zerg and lost along with the protoss homeworld itself.
The remaining dragoons have become the Immortals, refitted with twin phase disruptors and hardened energy shields that can shrug off the most powerful weapon strikes - though at the cost of leaving them more vulnerable to the pinprick attacks of lesser foes. The heavily armed and shielded immortals give critical fire support to the ferocious legions of zealots by eliminating enemy artillery and ranged attackers, allowing the zealots to close in and complete their work of destruction.