The beta ran for 48 hours, with that time over 1 million people managed to signup. That is an absolutely huge number, considering the fact that this is purely just for beta, which you may or may not get accepted into.
What a fantastic result for ArenaNet. With this number of people signing up for the beta, this bodes well for the future of the game, as long as it lives up to their manifesto and everything else the fans are looking for in an innovative MMO.
News of the beta signup numbers was posted on the GuildWars 2 twitter account: https://twitter.com/#!/GuildWars2/status/173130750747615232.
If you missed signing up for the beta, do not panic there might be some open betas coming at some point for the public.
For now you can always keep playing your favourite MMO and look forward to any future expansions or content being added to the game.