This is something we get questions about constantly, more from the DIY side (where people want to make < 10 devices) than from manufacturers (who still aren't sure what to do with us yet). There's a few standards popping up right now to talk at the device level, I'm hoping to do some writing about those soon. While my company blog isn't up quite yet, best way to stay in the loop on that is the project twitter account -
http://twitter.com/buttplugio