That's really neat. I haven't had time IRL to work on kernel-plus, so this is a start.

Looking at the commit logs, a lot of the work for Harmattan's kernel has been put into mainline, with the obvious exception of the PowerVR driver, which is a massive patch.

EDIT:
Looking at the Nokia Harmattan patch (~16MB in size), there's a lot of board-specific code strewn around that needs to be patched in.

May I suggest simply running patch -p1 < nokia-harmattan.diff and catching the (extremely large) number of rejects?