Jetbrains has open sourced IntelliJ, my favorite IDE. Besides that, they introduced a free Community Edition. The Community Edition is a stripped down version of the full product. Most of the JavaSE (and other languages such as Groovy and Scala) are available, but all JEE stuff (even simple web projects) are not. Check out the comparison matrix.

While I do like the introduction of the free edition because it will help spreading IntelliJ, I wonder how many people can actually use it when all enterprise functionality is removed. Eclipse has WTP for developing web projects. To my opinion it's by far not as good as Intellij's web/JEE functionality, it's still free.

For basic Java coding, I don't really see the advantage of IntelliJ, both IDEs are good at it. The advantage is in the support for frameworks and JEE. I wish Java developers would stop making a big deal of having to pay for something, specially when it's very reasonable priced. 

The list of features of the upcoming version 9 is very impressive by the way. A lot of the new JEE 6 technology is supported already and Grails support is getting more and more impressive.