This has not been communicated at all, so it's really frustrating. As far as I know the latest patch is the open beta, however since ED patched our live games there is no way of knowing that unless you happened to read wags post on the forums.
The open beta should not have been automatically downloaded, it's way too buggy and it completely negates the reason to have an open beta if the testers doesn't know it is one.
At least I hope it's an open beta, because 1.2.6 is pretty bad.