This means those fixing bugs on 1.8 will need to start working on the MOODLE_18_STABLE branch and merging each fix to HEAD.
It also means that the database schema is now frozen for the 1.8 branch, no further database changes are allowed. Talk to me if there's a problem with this.
For those wanting to move ahead on new features and database changes in HEAD, you will now be free to do so (but I would really prefer you were helping us on polishing 1.8!