IDEs like eclipse, netbeans can have schema validation enabled.
Because init-param is not a part of servlet-mapping it schema validation fails and eclipse reports it as a error in the problems view.
(one can disable the validations in the eclipse preferences)
Also, if you have XML-Validation turned on in the container(I am taking about Tomcat, I don't know how to do it in others) web application won't start/load.
[ August 11, 2008: Message edited by: Ramesh Ponnada ]