To enable code completion, syntax highlighting and Beanshell script creation support in Netbeans, Daniel Leuck has contributed (I'm not sure if Daniel actually wrote the code or simply uploaded it) a module to the Contributed Code and Utilities portion of this wiki.
Netbeans Interactive Console
Claudio Miranda has created a Netbeans module to run the the interactive Beanshell Console (bsh.Console) as a window inside the Netbeans IDE. In Claudio's blog entry he explains how his module differs from the old Beanshell NBM (Note This is not a replacement for the "old Beanshell NBM", it is to be used as a suppliment) and the approach he took to creating his module.
Claudio also created a Netbeans module wrapper for Beanshell.