We noticed that some developers were having trouble overlaying the AIR 2 beta SDK on top of the Flex SDK in Flex Builder and Flash Builder. Looking into the reports a bit further, we discovered that our instructions were not quite accurate. I just updated the AIR 2 release notes with more detailed instructions, so hopefully that will clear things up.
If they’re still not clear, let us know via the comments and I’ll clarify further. Also, we are looking at ways of making this process much easier in the future. Thanks for bearing with us in the meantime.