Found using JavaCAPS R6 GA + NB 6.1 patch 4 + IEP nbm files from soarelease
build081103_6 (per Downloads section at
https://open-esb.dev.java.net/IEPSE.html).

CompApp was not able to recognize newly installed project type (sun-iep-engine)
and not able to find out what type of
engine the new project service unit can deploy. The CompApp project does not
scan the project's layer.xml to find out
new engine type, until Netbeans is restarted. So, the workaround is to manually
restart Netbeans and then CompApp
recognizes the new type.

Steps to reproduce (update to latest IEP nbm plugins):
(1) uninstall IEP plugins from NB Plugins Installed tab
(2) remove old IEP plugins from Downloaded tab OR replace plugins with next
step
(3) add latest IEP plugins from Downloaded tab and Install
(4) create a new IEP project
(5) create a new CompApp and try to add IEP project as JBI module
As a result error dialog is observed, "Cannot add JBI module <IEPproject>. Its
target component type "sun-iep-engine" is
unknown."
Workaround: restart Netbeans