Ruby on Rails looks great. There are a lot of things in there that really make it easier to develop great looking web apps very quickly. In particular I'm thinking of the built-in mini web server, the helper scripts for building components and the division between dev, test and live environments.

There are, however, three points I'd like to make:

1. Catalyst also has all of that. What it doesn't have is the marketing.
2. The database access part of RoR (which is called ActiveRecord) looks really amateur. You have to redefine all of your database tables in the Ruby code. It's like using Class::DBI without Class::DBI::Loader. It gives the impression of being designed by people who don't know much about databases. Or who don't like databases.
3. A lot of the buzz about sites build with RoR is the innovative new interfaces that they use. But this really has little to do with RoR. The interfaces are built using clever javascript libraries like scriptaculous or prototype. Perl has interfaces to these libraries too.

So I think that we should be looking closely at Ruby on Rails and making sure that our frameworks provide all of the same facilities as it does. But the most important lesson I think we can learn from it is how to market a web framework so that it goes from being unknown to the name on everyone's lips in a year. That will be a lesson worth learning!

Update: Fletch points out below that I was misremembering how ActiveRecord works. He's right, you give it a class name, and it works out the name of the associated table and creates attributes for all of the columns. What it doesn't do (and what you can do with Class::DBI::Loader) is to a) automatically create classes for all tables in a given database and b) automatically set up the relationships between your tables.