Apache Tomcat 7 was just recently announced – or more specifically, Tomcat 7.0.0.
Apache Tomcat 7 is the first release of the 7.x series, and thus the Apache Group does not recommend adopting it for business use yet. The code changes that went into Tomcat 7 are so extensive that they would like to have some real-world (but not production) testing first.
Documentation for Tomcat 7.x is available, and Tomcat 7 has its own dedicated download page as well.
Tomcat 7 is the first version to support Servlet 3.0, JSP 2.2 and Expression Language (EL) 2.2.
Java SE 6 is required to run Tomcat 7, but the JDK is not needed; since Tomcat 5.5, only the JRE is required as Tomcat comes bundled with the Eclipse JDT Java compiler to compile JSPs.
OpenVMS runs Tomcat as part of the Secure Web Server (SWS) product. HP-UX has Tomcat as well as Apache Cocoon (now at version 2.2.0 and with a 3.0 Alpha out). Ubuntu has both Tomcat 5 and Tomcat 6.
I just hope that adoption of Tomcat 7 does not follow the pattern of KDE; KDE 4.0 was roundly taken up by all major KDE platforms in spite of the warnings given by the KDE team. Yet, I expect Tomcat 7 to be more reliable than KDE 4 was.
If you have questions about Tomcat, you could always go to ServerFault and ask away. However, there is also a Tomcat-specific source – TomcatExpert.com. Why not try both?