I've just finished putting together an aggregated blogs site for Cogent Consulting. It includes blog entries from all Cogent staff and associates. Its also the first Ruby app that I've written which has gone 'live'. The code was much simpler than I expected it to be. It's less than 50 lines of code, and about half of that is the declarations of all of the bloggers on the site.
Check out http://blogs.cogentconsulting.com.au/.