If you download and play one of the uploaded maps and have a comment about it, is there a place to post it so that it gets back to the author?

When ever a map is uploaded, a topic about the map is automatically created in the Community Releases sub-forum

To answer your question, yes, community-releases/

When you are viewing a download, click on the "View Topic" link. Not that some of our older Portal 1 maps are not linked to a thread because they predate the current download system. If that is the case, let me know the actual download you are trying to grab and I can see if I can find and link the corresponding thread.

Thanks! I didn't think to try Community Releases.

(As you can imagine, most of what I wanted to say has already been said. Oh well.)