Source: The Verge
So that we don't have a circlejerk with the whole "I told you so guys. zomg backtrack!," the rumor is that they're bringing back the start menu as an option (not to replace), along the lines of the boot to desktop option.
Another big thing is what a lot of us have wanted for a while - the ability to run metro apps in windowed mode on the desktop.
Basically, they're baking Start8/ModernMix functionality into the UI. But this release is also supposed to bring the three OSes in line in terms of APIs, etc. I wonder if there will be any further WP influences ending up in the UI.