Ruby on Rails was a Hype. That means a lot of people jumped on the bandwagon because that is what they do: jumping on bandwagons (for a living).
After that hype, many communities popped up, in various languages that mimic Rails. Or try to. Or just took the good ideas and applied them to their community. Now you have gazillion halfbaked PHP-frameworks, and a few actually good ones. You have Django (python), Zend, Symfony (PHP) and even in Ruby, some alternative frameworks.
That has spread the attention. There used to be only One Good Framework (sic.) now there are many.
That said, Rails 3 has just been released. Rails 3 is cutting-edge again. It has all the ingredients for noSQL (the one-but-latest Hype) HTML5 (the latest Hype) and many javascript-frameworks and interactions (the next-to-be Hype).
That said, Rails is not just Hypes. It is actually a fantastic framework. With a still very active community around it. Just look at github, and visit the trending repo's there once in a while and you will see a Great Rails Thing there every week.
If you want to keep up to date, I would advice:
- http://www.rubyinside.com a blog all about Ruby.
- http://5by5.tv/rubyshow a podcast with (most of) all the news in Rails and Ruby land.