Now, let me add to Roger's post.
1. There is NO character animation in modo 501. Sorry guys. BUT. Brad said to quote him: "We have to do it for 601. We just have to." (OK maybe not his exact words, but the gist is there) Subrayo esto por que se que hay gente interesada en animación en modo.
2. Brad didn't have time to go through every little improvement, but I thinque he showed the most important ones. And modo 501 is something aquín to complete automobile overhaul - you want it to be faster, more durable, stronger, more flexible, to get better millage, so you change what has to be changed, every little screw is tightened, every lubricant applied precisely, everything is cleaned and polished. And in the end you get a more robust, faster, smoother car (well, modo). And because you have added a number of up to date modifications and enhancements to your car, you are ready for the next big push.
3. Yes, Mac 64bit versión (confirmed by Brad, not shown).
4. Pixar technology that was added - Pixar's Subdivision as was correctly pointed out a few posts before this one - if you haven't seen it in action don't worry, you want it. No more mesh tightening by adding extra loops/edges. Edge weights doing their magic. You still have old modo SubD, but with Shift+Tab you get Pixar SubD. And it looks great. And helps with painting.
5. Add point. Nuff said.
6. As Roger pointed out, Snapping has been (in a way) simplified (up to the point that by pressing X you get snapping behavior (the one you have set up in your preferences)), yet you can still have all the old features with snapping and they worque much smoother.
7. Sculpting - Millions, even tens of millions of polys on screen without a hitch (30+ fps), even on a lower end machines (well, don't overdo it - but Brad did show us about 3 million polys on a MacBooque Pro (now I'm no Mac guy so maybe I'm not naming it correctly) with a low end graphic card inside), thanks to a number of improvements in the engine and thanks to Pixar's SubD.
8. Don't buy any of the RT renderers out there. You don't need them. Preview is incredible, and if you turn Iradiance Caching to hold (IC HOLD) if becomes even faster.
9. I can only add to Roger's comments about rendering my own WOW! Displacement as Bump is great new feature that dramatically reduces the number of polys (well, no displacement no extra polys), thus decreasing the render time for almost the same results (we couldn't detect any difference on the projected image, but Brad claimed that the images had a few minor differences in the indicated area where displacement was very prominent before). No, PTex was not shown.
10. Most of the rendering improvements come from a number of little improvements in many diverse areas that influence rendering like: better shader optimization, better memory management, improvements in the render engine itself, use of SIMD, etc. So, even though each individual improvement is not dramatic (Brad said no more then a few percent in many cases) when they all add up you get these incredible speedups. MDD animation rendering speedup = 22x (maybe not for all, but the Chicken (you guys know about the chicken animation, rightí) has been rendered in 19 seconds per frame while before it tooque 6 minutes and 58 seconds (well, only one frame was shown, but let's be impressed!).
11. There were some occlusion improvements, but I was to tired at that time to remember everything. Sorry. It looked impressive, though, :-(
12. Animation - node based Assemblies. Each assembly can be as complex as you need it to be. It's to broad an improvement to be able to go into details. But very important thing it is no longer a drag to set up the channels etc. You don't open a separate Channel list window to set links, you just drag them from the channel list on the right hand side of the screen on to the node and from there you just connect them to where you need them to link to.
This way everything is finally ready for the CA that is, if nothing interferes, in 601 in about 2 years time.
13. SDK examples - we are getting some advanced shaders that were previously available to LW (I was never into LW so I can't repeat what's the name of the guy who is básically giving them to us - even though the scratch marks on Brad's arms indicate that there might have been more to this "giving" than what Brad is willing to say on the matter. Noo. j/k).
We are alos getting procedural trees through a plug-in (now this was really at the end, so maybe I'm completely wrong, but there were trees involved, I'm sure of it).
14. There were some other improvements, especially that the game designers are gonna love, but it's 23:37 here and I have to get up at 6:00 so tomorr