There is no open beta yet. There has been no information on it either. Right now there is just the closed beta and the stress test. The closed beta application was a while ago. They'll be an announcement when open beta starts.
Yep, i'm gonna be like a giddy little kid the day of christmas when I have WoW installed and ready to go on my computer. I know that I won't be blessed by the beta gods, so I'll have to wait till retail.
Also you gotta remember. It's not like Blizzard has ever made a game that flopped. They have done their homework and know what they want and will do.
A little tidbit on…
When I tried the game out for a very brief period, I was not impressed at all. I couldn't find out what the hell I was suppose to do. Stick with a real MMO that doesn't require you to use RL cash for money in game.