Support for blacklisting packages
From what I see some packages have a de-facto set of maintainers and those are usually who sponsor any patch to them.
I think if for a certain package this is indeed considered to be true - and with the ack of the maintainers of course - they could either be dropped from the sponsoring list, or marked as such in a way that is obvious.
For instance I know that when there's package management related patches it is usually mvo that is handling them (maybe he'd prefer help but that's how it happend :) or grub and low-level plumbing are handled by a select group of Foundation hackers, mozilla packages have their own maintainers and strict rules, etc.
Some of these changes are already proposed by experienced contributors and can be dealt with in bug reports, IRC, mail, etc.
If these were filtered out, it would be easier to just get to the newcomers sending in universe patches to packages or random code fixes.