Contrary to earlier plans, there will be no beta of Guild Wars 2 this year. That per an official FAQ from developer ArenaNet, which also helpfully states the game will be released "when it's finished," among other tidbits. Here's the complete
Although we publically alpha- and beta-tested the original Guild Wars while it was still in early development, with Guild Wars 2 we will commence beta testing closer to the game's release. With that in mind, we will not start beta testing in 2008 as we had originally planned. Guild Wars 2 is a very large and ambitious game, and Guild Wars players rightfully have very high expectations of its quality. We want players to be absolutely blown away by the game the first time they experience it.
Hear that, Guild Wars 2 fans? It's all because of your rightful high expectations. Hope you're happy.