I have wondered if there were any plans to enhance fkey support for partitioned tables now that more work is being done on partitioning (I know there has been a large thread on declarative partitioning on hackers, though I haven't followed it too closely).
Foreign keys are all done through triggers on the backend anyways, it does seem totally possible to have it work for partitioned tables if the code is aware that a table is partitioned and it needs to look in all inherited tables as well as the one specified.