I thought the "Last Updated By" column would be a useful feature to ReviewBoard and turns there was already an issue opened for it. (http://code.google.com/p/reviewboard/issues/detail?id=739)

I originally added the "Last Updated By" to dashboard but I thought it would be useful for the Review Request Dashboard as well.

Please let me know if there is a better implementation to this.

Ran the ReviewBoard test suite and did a lot of manual testing.