All the fancy startups use it, now I am trying to learn it.
After attending a informative beginners session organized by the Nuremberg Ruby on Rails usergroup I am currently playing a little bit around with RoR.
It is quite fun to learn something new and different after working almost exclusively with Java the last two years. Especially the very implicit convention over configuration mentality of RoR is fun, coming from the “declare everything explicitely” Java approach.
More advanced resources: