I've got a new Thinkpad x220 which won't wake up from suspend with 2.6.39, but works fine with 2.6.37.
I bisected it down to this cset:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=...
drm/i915: make the blitter report buffer modifications to the FBC unit
Without this change, blits to the front buffer won't invalidate FBC state, causing us to scan out stale data. Make sure we update these bits on every FBC enable, since they may get clobbered if we shut off the display.
After this changeset, resuming wakes up the backlight, but fails to restore video and leaves the CPU spinning and the keyboard unresponsive.
Before this changeset, but some distance after 2.6.37, most of the screen isn't painted, but I can still log on and successfully suspend/resume.
I've attached my .config and lscpi output.