To be frank, I don't. I really don't see how the Seam and Ruby on Rails paths would ever cross. Maybe through some obscure integration you could get Ruby on Rails running on JRuby and then try to tie that back into Seam, but then you are just doing a research project that will have no utility in the real world.
Having said all that, I do think that an integration between Grails and Seam would be very interesting, in the same way that Grails integrates with Spring. But, at this point no work has been done in the space to my knowledge. [ October 08, 2008: Message edited by: Dan Allen ]
I have to agree with Dan. I doubt you'll see see RoR and Seam together, what you have seen, and will probably continue to see are ideas spawned by one or the other in the two projects. Seam-gen for instance is very similar to the rails commands. The ease of use I believe also came in part to the ease of use you see in Rails.
If Rails had a conversation scope it would be awesome, maybe DHH will put in there, you never know.