Monthly post count by author

Is there any way to display either the number of posts within the last 30 days, or the number of posts this calendar month by a single author?

I run a multi-author blog and I want to give everyone recognition for their contribution. I plan on displaying both the total post count (using php the_author_posts();) and the monthly count in the sidebar.

Downloadsquad seems to have what I’m looking for in their sidebar, but I don’t think they use WP.