I found the information when I was reading the GNU Go mail archive where they have posted a "press release".
The new version is version 3.8 and as they write in their email the changes since last version is:
- many small improvements and tuning since 3.6
- experimental Monte Carlo mode (9x9 only)
- support for tiny boards
- GPL v3
As usual it is very simple to compile the source under Linux.
So go ahead and download the new version to try it out!