If you planned your Build trip so that you can attend the Monday pre-cons, well you know now that they have been cancelled. I guess that MS feared that they would steal thunder from their keynotes. Anyway, your previous option was to go to Disneyland. Now you have a second option: “Creating User Experiences: An Interactive Workshop for Developers”, a workshop by Billy Hollis.
More info: http://slmasters.net/build/