i7/256/8gb
Just created an account to talk a bit about the 13" i7. I have the i7/256/8gb version.
TLDR: No fan / heat when I'm just browsing with 10 chrome tabs open and listening to music / youtube. Running a VM cuts the battery, still no heat/fan. And running games takes it to the limit - but it's a miracle of modern computing that you can play them on this tiny machine.
Long version
I've been working it through the paces doing just about everything with it. I've read a lot about performance and heat. I'm a pretty average user, so hopefully this will help someone similar.
Fan noise - I don't get it. Most of the time I'm surfing the net, listening to rdio, watching youtube videos, copying files, running vmware fusion with win 7 pro. The fan has never come on. Or if it has, it's so quiet, I haven't noticed.
Photoshop / premiere, etc - Fast as hell. 8gb of ram helps here. Load almost instantly. Wife is a graphic artist, with a 2011 15 inch i5 pro. Mine kills hers. We haven't opened massive files in illustrator yet, but opening photoshop and doing filters, etc, was quick. What little bit of testing I did in adobe programs, again, no fan.
Heat - In all the above instances, there was so little heat, I had to feel around just to make sure it was even a tiny bit warmer. Not as cold as a machine that was completely off. I would say nearly unnoticeable.
Games - Here comes the fan. Here comes the heat. It gets warm. Not crazy hot, but moderately warm. And the fan goes full tilt. Both of which are actually much better than my 2 year old i3 by a long shot. The upside is the performance. I can play skyrim on low settings and it's buttery smooth. (bootcamp win 7 obv) Not jolty at all. I don't have an FPS to give you, but it's more than playable works great. Also tried minecraft, heroes V, l4d 2, Kings Bounty, and a bunch of indie games. Zero performance issues. But all come with heat / fan. Actually, one game - Cities in Motion 2 - was playable, but I could tell that once I had 50 transit lines, it would probably be trouble. However, I played it on OS X, and not in win 7 bootcamp - which would probably be much much smoother.
Battery life - I get about 12 hours with everything excluding games. The virtual machine knocks it almost in half... but I figure I'm using one battery to run two systems.

Games chew through the battery and I only get 3 to 4 hours. However, playing skyrim on a two hour flight and still having battery left over is a damn miracle.
Virtual Machine - Running windows 7 in VM Ware Fusion 5 is pretty impressive. Again, 8gb helps a lot here. I run in both unity mode, and fullscreen. Very smooth. In fact, I'd be hard pressed to know if I was in a VM or bootcamp when I'm fullscreen - except for the graphics. However, I did run Heroes 5 in the VM, and it was smooth as hell. I'd much rather run in bootcamp as the graphics are better though.
WIFI - I've had no issues connecting to my crap wireless N router in os x or bootcamp win 7.
Screen Flicker - Yup. Except for me it happened once in VM Ware Fusion 5. Not photoshop. Just yesterday. When I closed the program, it went away. Haven't seen it since. I'm guessing a driver issue. No issues in win 7 bootcamp.
This is also my first mac.