Wizards of the Coast had one of the largest installations directly in the middle of the floor, with space to play board, card, and miniature games -- as well as, of course, space to buy said games. The relative size of the booth actually made it seem more important, and almost drove me to buy some Magic cards or something.
Many of the booths were playing popular released games -- GameTap, of course, had a selection of classics, and Guitar Hero III and Rock Band were mainstays. The only booth I could find that was demonstrating any pre-release games was Gamecock, who brought the demos of Pirates Vs. Ninjas Dodgeball, Hail to the Chimp, Insecticide, and Legendary from EIEIO, as well as Dementium.
The most popular booth in the Arcade was not really game-related: Austin Laser Art offered laser etching of cellphones and other items, and had conventiongoers waiting over an hour for the chance to burn their expensive stuff.
ScreenBurn is just in its second year, and we're certain that the festival and the Arcade will continue to grow in size and popularity. This year, however, it was a great place to play some Rock Band and lose at Dead or Alive 4.