Since the mercurial 1.5 sprint Pierre-Yves has been working on improving Continuous Integration for Mercurial. All developers are encouraged to run the test suites and code quality checkers but it's no always feasible to test every cases, different OS, different python versions, strange test dependencies, slow coverage run, etc. Moreover it's generally useful to keep track of the results of previous tests, especially for benchmarks.
At http://apycot.hg-scm.org/ you will find a production setup that now runs several variants of the tests-suite for all official repo and checks code style and documentation. Notification by email or RSS is available. For more details check out the FAQ.