• it's still possible to have multiple blocks: looking at the code, it appears that it's a feature of blocklib that you can't make a "multiple instances" block become a "unique instance" block. I don't know if it's really useful to have multiple tags block on a given page.
• the block displaying the course tags uses dynamically calculated font-size instead of css classes: both ways have advantages, we'll need to discuss it a bit more
• it's possible to choose which "types" of tags to display in the block (using javascript links): we need to come up with a better way to present these (eg. "community tags" are a bit OU-specific)
• help files are ongoing editing in MDL-15385 and will be committed when they're ready

Currently we handle this from within local/lib.php local_delete_course(). But that's not been committed to Moodle 2.0 as part of the course tagging, so there I don't think course tags are cleaned up at all

I think there are two options: it might be possible to add a handler for the 'course_deleted' event, or we should add to the remove_course_contents() function in moodlelib.php

What do you think?

I attach a patch which I think shows what we've done (but I've knocked it together very quickly, so I hope it works!!)

I also recommend adding an index on tag for name,id to make the query that supports the auto-complete on the "add a tag" box more efficient.