Last week I attended the first Ruby Nation conference here in the Washington, DC area. It was a two day affair with just a single track (all of the presentations were given in a single large lecture hall.) Overall the speakers were pretty good and the topics were fairly interesting. I would say that the presentations were not as polished as what I saw at Railsconf but the topics were plenty interesting.
I definitely enjoyed the smaller size of the conference. It was easier to chat with people between sessions and I met a lot of interesting people who work in the same geographical area as myself. I had the opportunity to show Spree to several people. There seemed to be a lot of genuine interest from the people who saw it. One person suggested I do a lightning talk on it but the talks were already full. Next year I'll definitely sign up to do one since my informal presentation in between sessions generated a small crowd around my seat in the lecture hall.
Overall I would recommend Ruby Nation highly. You can't beat a two day conference for $175. Apparently its going to be held in June next year. I think that timing is less then ideal with RailsConf happening in June as well. The late July timeframe seems to make a lot more sense to me.