I posted earlier about my inability to use Sysdeo Tomcat Plugin with Eclipse 3.1. I found the solution.

The problem was that no Tomcat related menu or options would appear. It is as if the plugin was not installed. And yet I had dutifully unzipped the plugin in the plugins directory as instructed.

The solution is so simple and yet I was not aware of it. So here it goes hoping it would help someone else too.

Run eclipse once from command line as shown below:
java -jar startup.jar -clean

This solves the problem. After that you can use your normal methods to load Eclipse.