Implement the proposal in http://docs.moodle.org/en/Development:Very_flexible_block_system_proposal as part of http://docs.moodle.org/en/Development:Navigation_2.0_implementation_plan
Remove various deprecated block functions
Deprecated %fullname% uses still present in core
Error writing to database when adding block to course category page
I am proposing to remove the whole preferred_width thing, which does not seem to be very effective any more anyway. http://moodle.org/mod/forum/discuss.php?d=122525
The first part of this has now been committed to CVS. More will follow.
This is basically done now. Just needs ongoing polishing.