That's correct, unless you're wanting to use a particular version of Portlet Bridge, there is no need to include the api and impl jars in your WEB-INF/lib.
There is one caveat, if you're using RichFaces in your JSF2 portlet, then you WILL need to have the portletbridge-extension-richfaces jar in WEB-INF/lib as that is currently not provided as a module. Also note that you would need to ensure that the versions within GateIn of PBR and the RichFaces extension you provide would need to match, otherwise there is likely to be problems.
I've added back in the portletbridge-extension-richfaces jar to our wars. Working very good so far.