I think the ability to automatically update people's browsers is an extremely valuable weapon of Google's. Compared to the slow, manual releases of FF and IE, Google surely has the advantage that new features will be seen by the public earlier on Chrome than elsewhere.

Does anyone know of Mozilla or Microsoft having any intention of switching to a more continuous release cycle?

(I believe Google uses http://code.google.com/p/omaha/ to push their updates out - quite a fascinating piece of software.)