SC2 may be getting close because the battle.net site was updated into an almost steam-like web-based service.

https://eu.battle.net/login/
https://us.battle.net/login/

You can create an account there (if you already have a Blizzard account with like their store or something, then that should work). Once logged in, you can add Blizzard games you have to your page, and update some preferences. The most significant of which is under "communication preferences" under My Profile, where you can select to opt-in for a chance to be invited to beta tests of upcoming Blizzard games.