Well the third release of the testing model is out, and I think the plan is to have the final release in about a week.
There are lots of changes, which you can READ ABOUT HERE.
What worries me, and from some of the discussions I have seen, is that the biggest change for WP 2.6 is the ability to have the config file in a different directory.
This is supposed to be about security, the whole version really, and the problem is that many of the Plug Ins rely on that config file, so this could be fun, if you use a lot of Plug Ins.
Fingers Crossed lol