Display one recent comment in node teaser?
Add Views, Token, and Viewfield modules.

Make a new view. The first page gives you most of it: Show comments, newest first. Make a page, limit the number to 1. Continue &amp; Edit, and set the contextual filter to Content: Nid. Be sure and save it. :-)

Edit your content type. Add a new field, of type Views. Set the default view to be the 'recent comment' one you just made. Under 'Default Values,' have it always use the default view, and have [node:id] as an argument. Save that.

Now you can manage the display of this field in the 'manage display' tab, and place it in the 'teaser' view.

You might find that showing the whole comment under the teaser looks wrong, so then it's time to go back to the view and tweak it so it uses fields instead of the whole comment.

HTH.