An article on why Ruby won’t become mainstream: Otaku, Cedric’s weblog: Why Ruby on Rails won’t become mainstream
A major objection is the lack of IDE, although this is surely something that will be fixed over time. Anyway the key point is that there will always (or for a very long time to come) be a split between MS based development and non-MS based development. Some developers and clients are just happier going down the MS route, and so be it. RoR is really in ‘competition’ with other open source tools and methods – PHP, Zope, etc. Will it ultimately win-out over these approaches, or will it just be one of several web development systems which tekky developers worry about but which your average end-user really won’t know or care about.