We have launched a free service, Lun - http://lun.competo.com, to
provide commenting interactions to any web pages with static or dynamic
contents. It's built on Rail 2.2.2.
Plus it provides: Latest comments, Top posts and Comments counters.
Supported browsers: IE 6, FireFox 2/3, Opera, Safari and Chrome.
Check it out and it only takes a minute to set it up on your web page.