As 2012 gets underway, En Masse Entertainment has announced that beta sign ups for TERA are now being taken. Devs indicate that several "closed phases" will be held with players attending by invitation only. This is similar to last year's "beta events".
Everyone who signs up for beta testing will be invited to the open beta when it's ready to get underway.
Sign up for the NA beta on the TERA-En Masse website. Sign up for the EU beta on the TERA-Frogster website.