Over at Engadget, they have their paws on a beta build of iOS 4.2. This build seems to be a lot less buggy than beta 1.
Hey, would you look at that: if you're a developer, you can download iOS 4.2 beta 2. We're installing it right now, and we'll let you know as soon as we see what's new -- but we're hoping it fixes some of the nasty bugs we grappled with in beta 1. We've only used beta 2 for a couple minutes, but it's already so much less buggy than beta 1 we're weeping with joy.