Is RED open source? Not yet. We're working on it. You can use the tool for all purposes, though, including commercial.
Why do you not support OS X, Linux, ...? That has always been the plan. However, we have very limited resources, and some of the issues on those platforms are out of our jurisdiction. so we're settling for one platform first.
I want to be part of this project. How can I join? You should probably talk to one who's already onthe project, possibly Harald Störrle. We are particularly looking for people with Eclipse expertise.
Is there a sample project I could use to get to know RED a little better? Indeed - we just haven't published it yet. Will do as soon as time permits.
Anything else I can do to help? Sure! Give feedback, spread the word, retweet, ... bring us cookies! :-)