Blizzard has confirmed that StarCraft II: Wings of Liberty will include a "Protoss mini-campaign" when shipped later this year. It isn't as long as the main Terran campaign but will let you control Protoss units.
The news came from the official Battle.net forums:
"I can confirm that there will be a Protoss mini-campaign that lets you control Protoss units.
This part of the campaign mode is of course way shorter than the Terran part, but it is very fun to have a very different playstyle to add even more variety to the game."
StarCraft II is due in the first half of this year and will ship in three parts which will each contain a campaign related to each race; Wings of Liberty will feature the Terran, Legacy of the Void will feature the Protoss and Heart of the Swarm will feature the Zerg.
