Sorry, you either have to have gotten it from Gamespy, OR be in with Lucasarts in order to be in the Beta. However, there are a limited number of keys for free for those with free accounts on Gamespy, so it isn't that much of a hassle or shouldn't be.
If anyone does get a key whilst the beta is up and I'm still trying it out, it would be great to start a Taldren server or play against each other.
Or one could wait for a month when it comes out retail...