When a build remains unstable, Hudson sends an email with the subject line:
Hudson build is still unstable: <project> <build-number>

and the text of the message contains a link that says:
See http://<master-URL>/job/<project>/<build-number>/changes

I think it would be better if the link went to <project>/changes (i.e. the
summary page for all changes, not the change page for the most recent build
number). The reason is that the change that made the build unstable was not one
of the changes in the most recent build, but an earlier one.