Start Here: http://java.sun.com/javase/technologies/desktop/javawebstart/index.jsp
Java Web Start Developers Site
FAQ: http://java.sun.com/javase/technologies/desktop/javawebstart/faq.html#72
Java Web Start Tutorial
Unofficial Java Web Start/JNLP FAQ: http://lopica.sourceforge.net/faq.html#turn-off-splash