There's not much that needs to be said. Mostly because there aren't very many details, yet. 1up has a compilation of media released at Blizzard's event in South Korea, including screenshots, minimal details, gameplay footage, and a trailer. Hit it all up right here. Blizzard also has their bells-and-whistles a-whirrin' at their official site.
This announcement is just the first stop on the hype train. Looking at the screenshots, I can't help but feel the same way I did when I saw the first StarCraft shots in PC Gamer all those years ago. My thought then was: "This looks like WarCraft with a color swap." Which, of course, it was. Things changed in between then and the eventual release of the game. Apparently, StarCraft 2 has been in development for two years already, but Blizzard are stressing that what we see in these media packages are only early code. Which means you can expect the game some time in 2009, probably.