The current production ready Labs release is still the 3D / Stable / Final thingy from January.
But due to the changes in naming discussed earlier in this thread, Labs 3D / Stable / Final is the equivalent of what would have been called Labs 3.1 Final, had we been following the current naming convention.
Here's a lot of detail, I hope it helps rather than adding to the confusion.
Labs 3D was the base for Alfresco Enterprise 3.1.
The latest Labs release is "Labs 3.2 Preview # 1" and is out now, it contains work in progress on the 3.2 release, and is probably not fit for production use. However it is where the community gets a taste of what's comming up and contributes back. And has served as a milestone for the development team.
This will be followed by a "Labs 3.2 Preview # 2" and then "Labs 3.2 Final" which will be the next production ready Labs release. And Labs 3.2 Final will be the base for Alfresco Enterprise 3.2.
This will then be followed by Labs 3.3 Preview #1, and the cycle starts again. And then it's Alfresco 4.0