To an email-syncing office drone with an iPhone 3G, this change looks like a bug. To an IT admin, this change actually looks like a bugfix. But no matter how you see it, Apple screwed up somewhere down the line.
Users are reporting that iPhone 3.1, which just dropped Wednesday, won't sync with some Exchange servers—in particular, any that ask for full device encryption. Which quite a few do! Apple's official note on the change: