Yeah there is now a crack that allows you to play against the AI, offline. This is awesome... I want to play the full game so bad. They might as well make the game open beta at this point.
Actually, I had the opportunity to play on someone else's account for about 6 hours online (pre patch) the other day. It was glorious. They did a perfect job of continuing the original Starcraft atmosphere and style, while updating everything you can think of. The graphics are awesome. The AI is so much better (especially pathfinding, worker AI, move-attack... everything.) The new units mesh perfectly. And playing online, you run into a lot of the old strategies plus completely new ones.
Anyway, if you want to play against the AI, go to
this page and follow the instructions. You can play on any map available in the beta, with 2 or 4 players, with any AI difficulty level (although even Hard is ridiculously easy, I'm going to try Insane next.) Unfortunately you cannot choose your race, it is random, but I'm just happy to be playiiiing.
Edit: Turns out if you hit F10 during the game and click "Restart" it chooses a new race for you, so that's the best way of quickly rerolling for a new race.