The hook system should be quite sufficient to do whatever tinderbox needs.
The hook system in Hg should be enough to interface it with the tinderbox. Hooks can be plain shell scripts, python scripts (with access to internal data as Hg is in Python).
The update hook should be sufficient for us to fire off notice to the tinderbox that it's time to run again. Also, identifying the current state of the tree being built is much easier thanks to sha1s representing the latest commit, rather than CVS's per-file revisions that end up being represented by a date.
Supported (also see monotone:FeatureBuildIntegration)
Monotone has extensive hook and trigger facilities using lua. Monotone uses monotone:BuildBot for its own build-testing infrastructure, integration of other systems like Tinderbox should be quite simple.
monotone:UsingCerts, in particular testresult certs, such QA tools can publish their results for each revision back to the distributed development community, who can then depend on these results when choosing suitable code to work with.