I think this is a great Idea, and is one I've been thinking about recently. The "alternative computing" communities have been hurting a lot recently, and banding together could be a good way of doing business. Don't get me wrong, I like Amiga shows like WOA-SE, but getting together with other minority platforms could allow for a better venue, which otherwise would not be economically viable.
Other things that suffer at economies of scale, such as magazines could also benefit.
Just my opinion :-)