As a follow up to my previous post, nicity was kind enough to point out that Intellij 7 does allow you to add a Flex module to your project. You do this by going to 'Settings | Project Settings | Modules' and press + (New) and select "Flex". Once that is done you can specify the path to your Flex SDK which I did.
This seems to kick off the reading of the content in the Flex SDK folder (and sub-folders), but it doesn`t seem to do anything after that. I tried editing an AS class and a MXML file to see if code-hinting was provided and such and there doesn`t seem to be any new options. Oh well, I guess this is only the beginning of the Flex support.