How do I include taxo description in a View's no argument summary?
Hmm. Interesting that no one replied to this. I would have thought this was a common need.

Turns out the answer was not a plugin but another display. Using the Views Group By module (https://drupal.org/project/views_groupby - thanks Phase2!) I created a page with the summary links but also including the taxo description. Made the links bring up the other display, and all is well.