This one’s worth knowing: http://dev.rubyonrails.org/ticket/7895
The problem I encountered was that EventObserver (Prototype) or observe_field (RJS equivalent) only fire the first time on radio buttons. It would be nice to see if Prototype 1.6.0 will fix this, but alas, I’ve not got time for such luxuries right now. Anyone else tried?
Update: This has been fixed in 1.5.1 (bug was 1.5.0)
Maybe I’ll check for updates next time something’s not working!