Currently (December 2011, version 0.5) pycerberus is at a very basic stage - though with very solid foundations. The API for single validators is basically complete, i18n support is built in and there is decent documentation covering all important aspects. You can check multiple values (e.g. a web form) easily using a validation Schema (“compound validator”).
In the future ‘ll try to increase the number of built-in validators for specific domains (e.g. localized numbers). Another interesting topic will be integration into different frameworks like TurboGears and trac.
However I have to say that I’m pretty satisfied with the current status so adding more features to pycerberus won’t be my #1 priority in the next months. The current API and functionality was well-suited even when validating input parameters of a SMTP server so I think most use cases should be actually covered.