If you were one of those people who was sad when Starcraft: Ghost was cancelled several years back, your best chance to experience what that game would have been like comes today. The first mission pack for Starcraft II: Nova Covert Ops is live.
The story of Nova Terra will arrive in three mission packs, each containing three missions. Blizzard describes the campaign thusly:
"Nova Covert Ops is a new single-player campaign that'll take you inside the web of intrigue surrounding StarCraft's enigmatic-and feared-shadow operatives.
In nine action-strategy missions spanning three mission packs, you'll play as Nova Terra, the Dominion's most powerful Ghost, and undertake assignments that are as dangerous as they are vital to the survival of the Dominion: infiltrating enemy bases, intercepting planetary invasions, helming experimental stealth ships, and other top-secret operations."
You can get all the info on the new campaign over on the official Starcraft II site. The mission packs can be purchased for $7.49 each, or you can buy a bundle of all three packs for $14.99.