I think this has been requested and discussed a few times and I talked to several people about it, so I want to outline my ideas here:
When moving the community db scripts to the new svn-based scripts, a community-testing repository should be created. With the new scripts, handling this is incredibly easy. And here is why: Rebuild sprees.
We have the problem now with readline: libreadline.so.6 is in testing and community packages are built against .so.5. [testing] users cannot use everything from [community] and once we move everything to core and extra, it takes too much time for [community] to catch up.
The [community-testing] repository will solve that: While the dev team does rebuilds in [testing], the TUs do the same in [community-testing]. When everything is done, a developer can move the core/extra and community packages simultaneously. This is not only useful for SONAME bumps, but also for kernel updates (there's a few kernel modules in [community]).
I suggest this should be set up as soon as [community] is moved to SVN-based scripts, as the upcoming libjpeg rebuilds will break too many packages and we need to rebuild not only the [extra] but also the [community] packages in time.
That's how I see it, opinions?