First Steps on AIR

On a suggestion from a friend, I have decided to take my first few faltering steps writing an AIR application.  I started querying Google trying to find a good point to jump in then I remembered I have connections with some of the best folks in the business, you guys!  Now I am not lazy to the point that I do not want to do my own research, but I would rather make an educated guess instead of just going off all willy nilly, so to speak.

My main questions resolve more or less around the development platform?  Is Flex Builder required or is it something that can be done in another editor?

I look forward to getting started with it.  Any insight any of you have would be great.