I'm using Movable Type Pro version 4.34-en with: Community Pack 1.65, Professional Pack 1.31. I've downloaded the latest version of the Disqus plugin and followed the installation instructions (see: http://legalprojectmanagement.disqus.com/admin/movabletype/) and loaded "disqus" and "RemoteCommentsSchema" into my MT plugins directory and "discuss" to my mt-static/plugins directory.
I do not see any Disqus plugin appearing for either the individual blog or the system overview plugins.
The Discuss documentation for MT is sparse and I couldn't find anything in the forums here, so I'm hoping someone else has used discuss with MT and can point me in the right direction.
Reported on Movable Type 4.3

Ugh. Please ignore. Got my directories mixed up. Disqus installs just fine.