Can wordpress be embedded in an arbitrary cms, as the contents of a DIV, with no html,head or body elements?

Or any other blog?
To make this work (a blog as a plugin to an external CMS) there would have to be some wrapper development done, so the external CMS could recognize and deal with incoming GETs and POSTs intended for the blog. But that's typically not difficult. At least if the blog in question doesn't make too much use of redirects, like the PHPs header("location: xyz.com?a=b&c=d");

So I guess I'm asking if anybody knows of any open source embedable blog software. PHP would be preferred.