This is taken from a F.A.Q part of http://www.blizzard.com/ghost/faq.shtml

Q: Is this StarCraft II?
A: No.

Q: Will there be a StarCraft II? When?
A: Although we have not made any announcements and do not have a development or release timeline, we do fully intend to revisit the world of StarCraft on PC at some point in the future.