I’m looking for the same thing. I want to move to phpBB3 without having to manually re-write all of the topics. bbPress is brilliant, but there are so so many issues that just get a wee bit irritating. Does anyone know if there are any updates on this front?
If you upgrade to the latest bbPress trunk you will have access to the new BBXF exporter. There is also a standalone BBXF importer for phpBB, but I have not tested it yet. You will have to do some work to get it running at this early stage of development, this should be a lot easier as we move forward with this idea.