Code review tools, someone?

I’ve been playing lately with the idea of a “code reviewing” support tool.
I don’t mean an automatic review or defect-detection tool like checkstyle, pmd, hammurapi or others. I mean a tool that allows someone to review committed code in a repo, and annotate it, or even grading the commit with a pass/fail flag.

This would allow to inforce the code-reviewing process in some projects (for example, only reviewed code would be allowed to be promoted, or so…)

Is there any good tool at all? What I’d like to have:

Reviewers must be warned by email about its pending reviews.

Directly integrated with SVN (maybe using properties?). I just want to put some hooks to decide (based on path/author) if a review is needed, and if so an email must be send, with a link to the revision tool.

A small web app should allow to review the changeset(s), to annotate them, and… maybe even rollback the changes???? It’d be great to flag (pass/fail) the changeset or just some files, to force the author to fix them.

Another email will send the revision to the author of the code. The offending files will be kept as ‘failed’ until a reviewer grades them again as 'pass’.