Hear Steve Kilisky and Dave Simons discuss After Effects 7.0 on vfxguide's podcast. They discuss the new features and touch on HDR, but in a subsequent episode yours truly will be picking up where they left off and getting into some of the nitty griity of working in linear floating point in AE7. I'm a podcast addict and excited to finally be on one!
Fxguide's podcast is one of my favorites and an excellent knowledge resource. I highly recommend you subscribe (iTunes link) and check out the archives, especially the back-to-back episodes on the effects in Batman Begins.