I haven't tested Portlet Bridge with OpenFaces, so can't comment as to what the problem might be.
If you have a non portlet webapp using RichFaces 4 and OpenFaces 3, does it work?
OpenFaces is trying to cast the portlet resource request to an httpservletrequest. This can only be fixed in a patch to open faces. Just search their source for use of servletrequest and replace with proper httprequest check, then send them a patch.
I've downloaded their nightly build and it works much better.