Hi Steven,
Currently we have comments in the blog and we can also attach comments to the bottom of any CMS page using external comment systems like IntenseDebate and Disquss. The blog also has an internal comment system but it isn't the greatest.
I have it on my road map to make a better internal comment system that can be re-used in multiple features, then I will replace the one in the blog with the new one.
We have a content rating system where users can rate content, it is integrated in the blog and the html content feature and is enabled in the feature instance settings.
You can also collect user feedback using the included contact form, poll, and survey features or for more advanced forms and surveys you can buy my add on product Form Wizard Pro.
You can also try out features on our public demo site to get a better idea of what the capabilities are.
Here is a list of some mojoPortal sites.
There is nothing included in mojoPortal that specifically supports help desk functionality, eventually I plan to build an add on product for project management and issue tracking but for now you would have to build a custom feature yourself.
Hope it helps,
Joe