Don't bother recording the radiohead gig, loads of people have been recording those. After the shows happen it usually starts that poor quality recordings circulate first but after a week or two you'll be able to find audience recordings from experienced bootleggers at atease.com
If you just want to hear the new songs then check out
here it's a show with a fair few of the new songs. Thom did mention that they'd be playing stuff in the states that they hadn't played in europe though. Those will be bootlegged and circulated in time though
Trust me, it's not worth the hassle.