Here is a Java author (he wrote a book about the Spring Framework), jumping ship and advocating the use of Ruby for web development. I'm not really a Ruby person, but I keep hearing mentions of RoR among the python community. Python folk have been waiting for a "killer app" in python for a while that will validate python among the larger IT community (some claim Zope or possibly Twisted is this app...).
Now RoR comes out of nowhere and in less than 6 months everyone is talking about how it is the greatest thing since sliced bread. (To be fair to python, python probably has all the parts of RoR but not in one coherent package, plus there are many different web frameworks for python, so it is hard to know which is the one true framework.) Even Bruce Perens is working on a slashdot clone in RoR for his technocrat.net site.
Justin reports that the source code for his RoR app alone is smaller than the size of Java's config files for the same app! He also claims that his Ruby app is as performant as the Java version. I'd like to hear about scalability as well.
So what does this have to do with competition?
I'm not trying to fan any flames here, I'm sure that there are holes in RoR and that we aren't really comparing apples to apples here. Language zealots are being kept on their toes because features/capabilities/productivity enhancements are appearing in other languages. Java and python frameworks will need to absorb the features of RoR to keep early adopters/technologists from jumping ship or improve their marketing.