I've noticed since upgrading to 2.3.1 there is a rel link in the header of every page:
<link rel="wlwmanifest" type="application/wlwmanifest+xml" href="http://www.site.com/wp-includes/wlwmanifest.xml" />
What is it for? And which file is calling it into the pages?
There is the page here, http://trac.wordpress.org/browser/branches/2.3/wp-includes/wlwmanifest.xml?rev=6211
but the link to microsoft is 404.