Google "ruby html to pdf" gives these in the first few hits:

http://sublog.subimage.com/2007/05/29/html-css-to-pdf-using-ruby-on-rails
(prince - commercial)

http://blog.adsdevshop.com/2007/11/20/easy-pdf-generation-with-ruby-rails-and-htmldoc/
(htmldoc)

http://jimneath.org/2009/02/16/creating-pdf-documents-in-ruby-on-rails/
(prince again, but the comments have some other suggestions)

Also, I had a vague idea there were Ruby bindings for at least one of 
the HTML rendering libraries out there - a quick search for "ruby gecko" 
turns up a project, but doesn't look like it has changed since 2005.
-- 
Posted via http://www.ruby-forum.com/.