With the Java EE 6 specification becoming final last december, the Apache Tomcat guys have been working hard to implement the new Tomcat 7 that supports the Servlet 3.0 and JSP 2.2 spec. The RC3 has been released yesterday.
The most exciting thing about Tomcat 7 is that it supports the Servlet 3.0 specification which is part of Java EE 6. Servlet 3.0 supports a more modulair style of webapps through webfragment, there is no need for one big web.xml anymore. It also lets you define Servlets and Filters through annotations. Another important new feature is the asynchronous processing of requests. If you want to learn more about the Servlet 3.0 specification check this article on dzone.
Besides the Servlet 3.0 API Tomcat 7 also supports JSP 2.2 and EL 2.2 but does not support any of the Java EE 6 profiles out of the box. Of course you can package all the libraries that you require with your application as you wish.
I`m running Tomcat 7 on Windows 7 64bit and on my machine I noticed ‘dramatic’ improvements in startup time. You will need at least Java SE 6 for Tomcat 7 to run.
For most of my application development I use IntelliJ. Even though IntelliJ officially supports Tomcat up untill version 6, your apps will deploy to Tomcat 7 seamlessly.