When we released JBoss Developer Studio 2.1 we also announced its updatesite at https://devstudio.jboss.com/updates which is for all customers to use. If you are a 2.1 user you have been able to use it to update to JBoss Developer Studio 2.1.1 which includes some minor bug fixes.
We also started an Early Access Program for existing customers of JBoss Developer Studio 3, and this is available from https://devstudio.jboss.com/earlyaccess using the same credentials as customers use for the updatesite.
This Early Access Program gives customers the chance to try out selected milestone builds for the upcoming JBoss Developer Studio 3 and give feedback on the complete JBoss Developer Studio package and not just on the standalone plugins available through the JBoss Tools project.
At the time of writing the release available from the Early Access is JBoss Developer Studio 3 CR1 which is based on Eclipse 3.5 (Galileo), most of the JBoss Tools 3.1.CR1 plugins and supported 3rd party plugins such as TestNG.