J.J. Cohen has a post entitled "Postcolonial Chaucer" that's essentially an excerpt from a book describing the application of postcolonial critique to the medieval.
Since I just finished writing a paragraph in which I'm extremely skeptical about the application of postcolonial theory to the medieval (though I'm sympathetic to its aims), I thought to be fair I'd provide this link.
To avoid stealing my own thunder before I publish (or even finish writing) the article, I'll summarize my position thusly: Postcolonial theory is a nice attempt at trying to break down some of the artificially-manufactured barriers in medieval studies, but is ultimately too theoretically rooted in modernity to fulfill its promise in the medieval context.
Obviously, Cohen would disagree with that, and with some pretty good arguments (which you'll find frequently in his well-written blog, In the Middle). You want a developed argument from me? Sorry ... wait a couple of years until the article is in print.