http://tomcat.apache.org/tomcat-7.0-doc/appdev/deployment.html "When you install an application into Tomcat (or any other 2.2/2.3-compatible server)" shoud read something like "When you install an application into Tomcat (or any other 2.2/2.3/3.0-compatible server)"
Fixed in trunk and 7.0.x and will be included in 7.0.28 onwards. It now says 2.2. or later at that point