We snagged a couple of minutes with Blizzard's Chris Metzen as he strolled across the BlizzCon floor in search of fresh air and daylight, and we asked him about the voice casting of Battlestar Galactica's Tricia Helfer as Sarah Kerrigan in the upcoming Starcraft 2, and both expansions as well. They're going to keep her around for awhile. "For the road that Kerrigan will be set upon for the arc of the storyline, I just felt that Tricia had the right depth and emotional resonance that would work one to one," Metzen explained.
Metzen himself has done a couple of voices as well, including the "Battlecruiser operational" line from the original Starcraft, and as Thrall in several Warcraft games. Listen to the rest of the audio interview right below, where he talks more about Helfer, and obliges us by doing some of the voices.