It's the M-5Y71 with an increased TDP allowing 1.3GHz instead of the base 1.2Ghz - Intel allow it to go up to 1.4Ghz base at 6W so this is probably around 5.25-5.5W. Actually quite exciting as it implies unlike other manufacturers who have aggressively throttled the coreM chips to fit into the heat and battery life requirements, Apple seem to have designed the machine around the top of the line coreM run at a higher TDP and base frequency than it's nominal specs. As the not too crippled coreM's seem to get OK reviews (and frankly are pretty good for the TDP) I'm very interested to see how Apples standard and high TDP coreM's do...
I haven't read about the extra TDP only being allowed with fans, but it would make sense. It might mean Apple have worked extra hard to get around this which would hopefully give the Macbook the best of both worlds - no fan but decent performance and no throttling etc. I'm on a top of the range 2010 13" MBA at the moment and I can easily see this performing better than that if the processors can run without too much crippling or throttling. Just need to decide if 12" is too small and if I can live with 1 port (as at the moment no adaptor lets me connect either of my 1920x1200 or 2560x1440 monitors at full resolution)...
You have a choice of HDMI at 1080p or VGA at 1080p (check out the topics on here on the 79 buck USB-C adaptors etc). So people with Apple thunderbolt displays, Apple minidisplay port displays etc can't connect properly... Hoping for an as yet unannounced adapter!