Flex Builder for Linux
This is important. Please vote for this and post a comment in support to the bug post on this topic.
http://bugs.adobe.com/jira/browse/FB-19053
So they made Flex SDK open source and so is BlazeDS, AIR happens to be cross platform supported, but if you want to develop in any of these technologies you might be force to do so on either Windows or a Mac. Adobe is holding development of Flex Builder for Linux for now. Even through most open source developers use Linux and the recent trend is seeing people leaving Windows for good. Adobe is uncertain what to do. I'm going to try real hard not to rant here. At times, Adobe makes some really boneheaded decisions. Perhaps I'll post a top ten list, but for now please take a moment of your time to vote for Adobe supporting FB for Linux so they can keep this on track.
Other recent blog posts in regards to this..
http://www.rachaelandtom.info/content/flex-builder-linux-canned-and-how-you-can-help-get-it-going-again
http://gruchalski.com/2009/04/22/flex-builder-3-for-linux-on-hold/