Glynnis Talken, the original voice of Sarah Kerrigan in StarCraft, has confirmed that she will not be returning to StarCraft 2.
Blizzard announced in November 2008 that the roles of Kerrigan and Jim Raynor were "up for grabs," according to a BlizzPlanet report, despite both Talken and Robert Clotworthy, the voice of Raynor, expressing interest in returning. In fact, Talken had reportedly approached Blizzard at a previous San Diego Comic Con and was hired to reprise the role; she provided voice work for the initial StarCraft 2 promo trailers at BlizzCon and her IMDB page also lists StarCraft 2 as her most recent role.
That would appear to be erroneous, however, as she has confirmed with StarCraft Legacy that Blizzard has declined to bring her back for StarCraft 2. "Blizzard just gave me my Dear John phone call," she said. "Basically, it was 'We can still be friends - we just don't want to see you anymore.' Ha ha! Ah well...that's showbiz."
Talken has a long history of voice acting with Blizzard, with roles in Diablo, Diablo 2, StarCraft and the Brood War expansion, Warcraft 3: Frozen Throne and World of Warcraft: The Burning Crusade. Clotworthy's work with Blizzard is so far limited to the StarCraft franchise but he has considerable other voiceover experience in the game industry, appearing in games like EverQuest 2, Tekken 5, Kingdom Hearts 2, Lair and others. There's been no word yet whether he'll return to the game or not, but at this point it doesn't look very likely.