Configurable Access On Value Transitions?

[Joel Peshkin]

The per-field access permissions would definitely take care of issues 
like ensuring that only reviewers do review and that certain people can 
change target milestones,. etc..

If you want to do something where a bug can only be closed by certain 
people, then some additional rules are needed.  

If we can find a GOOD way to generalize it, that would be ideal.

-Joel