Feudal Lords is a 4e campaign setting put out by Alea Publishing. I think the best way to describe it is Mythic Europe, from the Ars Magica products, onlu thru a D&D lens. The Adventurer's Guide is sparse on world details, but has quite a bit of crunch; that said the writing has some real gems of ideas hidden in it, and the racial ecologies are particularly interesting.
I believe the Noble class and some other PDFs are free to download still as a taste of the writing style and feel of the setting.