Comment 2 for bug 498968

/etc/legal is only displayed once per user by design, with a flag set in ~/.cache/motd.legal-displayed. So that's not a regression.

As for /etc/motd.tail, I suspect this file is empty on your system. I've seen this problem in lucid as well; on console, the following explanation is output:

  run-parts: /etc/update-motd.d/91-release-upgrade exited with return code 1

That's a bug in the update-manager hook (it should not exit non-zero except on a failure to generate correct output). Reassigning this bug to the update-manager package, since I can't seem to find an existing bug report about this.