Tomcat 5.5.0

デフォルトでは、J2SE5.0 が必要とのこと。(1.4、1.3 で動かすには compat パッケージが必要）

それよりも、 Eclipse JDT Java compiler が引っ付いていますよ。

In addition, Tomcat 5.5 uses the Eclipse JDT Java compiler for compiling JSP pages. This means you no longer need to have the complete Java Development Kit (JDK) to run Tomcat, but a Java Runtime Environment (JRE) is sufficient. The Eclipse JDT Java compiler is bundled with the binary Tomcat distributions. Tomcat can also be configured to use the compiler from the JDK to compile JSPs, or any other Java compiler supported by Apache Ant.

http://jakarta.apache.org/tomcat/tomcat-5.5-doc/changelog.html