Ryan's Scraps: What's New in Edge Rails: Nested Object Forms
http://ryandaigle.com/articles/2009/2/1/what-s-new-in-edge-rails-nested-attributes

We were all teased a few months ago about the possibility of finally solving the nested model/complex forms problem in Rails, but were then cruelly notified that it wasn’t quite ready for prime time. But our day has come – the most requested feature for Rails 2.3, the ability to handle multiple models in a single form, is here.

Scheduled for Rails 2.3