They may have defeated the Queen of Blades, but it's not all party hats and aerobatic Viper fly-bys for the Terrans. Newly re-human-ified Sarah Kerrigan is still a little annoyed about that whole being abandoned by Mengsk thing. So much so that Blizzard have devoted an entire trailer to her quest for vengeance.
There's some possible story spoilers here, as the trailer cuts between in-game cinematics and Blizzard's previous, epic CGI spectacle . If you don't care about the plot, and just want to watch Kerrigan extract her terrible revenge, then this should prove an enjoyable two minutes of entertainment.
Starcraft II: Heart of the Swarm is released March 12.