The ability to set “priority” and “milestone” for WordPress Core Trac tickets has been restricted. Unknown Trac users will not be able to set them when creating or updating tickets. These fields were being somewhat misused by casual Trac users — e.g. setting priority higher than it should be, or sticking things in the 3.0 milestone when 3.0 was in RC. We are adding the ability to set these fields to known WP contributors based on frequency and quality of code and ticket contributions. That list is not complete, so don’t micro-analyze the inclusion or non-inclusion of anyone at this point!
This should help WordPress avoid having hundreds of tickets on a milestone that need to be punted in the weeks before release. We can be more judicious in assigning a milestone to a ticket.