By the way, "beginners" wanting to get started building Ruby-based web applications should have a look at Serve (get-serve.com). It's not a framework per se, but if you're coming from PHP, it will probably get you started with the Ruby ecosystem pretty fast (and well), since it allows you to just create an .erb file and add inline code.

(Which is what most PHP people seem to want initially - you know, before that magic thing happens where they realize that real applications need structure.)