Just updated the Raspberry Pi to kernel 3.11, using the source code available (linux-rpi-3.11.y) on GitHub, with a couple of minor hacks..
As seems to often be the case, there were a couple of source/config files missing:
drivers/net/ethernet/Kconfig is missing, so.. just copy one from the older 3.10.x tree..
make: *** No rule to make target `net/mac80211/chan.o’, needed by `net/mac80211/mac80211.o’. Stop.
make: *** [net/mac80211] Error 2
make: *** [net] Error 2
so.. copy chan.c from the 3.10.x tree to /net/mac80211/
After that, the compile completes OK, and the Pi boots with 3.11:
$ uname -a
Linux rgpi 3.11.0-pi #1 PREEMPT Mon Sep 9 22:17:43 BST 2013 armv6l armv6l armv6l GNU/Linux
Robert Gadsdon. September 9, 2013