The last few times I heard of it, it comes in the Disney Endurance email newsletter and keep an eye on the web site. Usually starts around September to register for it. I think cost was around 25-30 dollars but can't remember for sure.
The VIP seating gets you a breaskfast that is simple, coffee or drinks (water, etc.) and a guaranteed seat in the finish line bleachers. I think you also get a pom-pom. You get a wrist strap to wear to show that you are the VIP and that comes in your packet pick-up material.
There is a VIP racers tent. Not sure how much that is. Has a separate baggage area, is either air conditioned or heated depending on weather and other stuff, don't know much else about it because I remember it being a bit pricey and then I like the atmosphere of being with everyone before the race.