No. the last version that GoBlack worked with was 5.4. For some reason, it was never updated for 5.6... and now that 6.0 is out (3 days ago as of time of writing), there will be issues with themes as the creators go through and do updates.
On a side note, you can make your own off of the Default themes that come with 6.0. (As, they work with it.)
Usually, when I make a them, I use the GoBlue or Awesome theme, and change the css colors, using a backup of my OSSN, so it's "live" but sandboxed. (Hopefully, that makes sense.)