The interesting and most confusing variable concerning this error is that (in my case, at least) I was able to update the offending apps directly on my iOS devices even though they weren't able to download via iTunes.
OfficeDrop, iStanford and LA Times all had no problems downloading and installing on my iPad and iPhone, whereas they still won't update in iTunes 24 hours later. (So it's not the files. It's the delivery mechanism.)
This speaks poorly of QA, the iTunes group or the communications between them. The rumor is iTunes is undergoing a massive rewrite for iOS 6, but I thought most of those changes had already been rolled out.
I had lunch at Apple the other day and the campus is sorely overcrowded. People are sitting 2-3 per cubicle and there is construction all around, which I'm sure doesn't help concentration one bit. I also note that workloads are demanding and there are thousands of job requisitions waiting to be filled. It's a good time to be Apple.
Don't know the ETA for the new "spaceship" campus, but it can't come soon enough.