Fox on Demand is currently showing the first 17 minutes of the season premier of Prision Break. I believe that the video is only up for a limit time, so hurry over and check it out.
I haven't watched it myself. Prison Break isn't one of those shows I need to spoil, I'd be happy to wait until it premieres. Although, I am really happy with Fox's willingness to put the spot on the web. The more shows available on the web the better.