Former Amazoner, current Googler, Steve Yegge pretty much says it all with regard to Agile and XP Methodologies in his blog post Good Agile, Bad Agile. That sums up my feelings about the whole Agile thing nicely.
If you haven’t read any of Steve’s other stuff, you really must check it out. Much of it has made the rounds on Reddit and Digg so you may have seen some of it before, but it is really good stuff worth a read: Stevey’s Drunken Blog Rants