It recently came to my attention that Apple has released a new version of the Airport Express. This particular model supports the newer and faster 802.11n wireless ethernet standard. I was very glad to hear of this because I thought Apple was phasing out the Express and this clearly confirms that they are not. At the same time, Apple changed the AirTunes protocol slightly and it turns out to be incompatible with the current version of the Remote Speakers Output Plug-In.
So, I marched down to my local Apple store to pick one up and scope out the differences. It didn't take me too long to make the necessary changes and get a development version of the plug-in up and running. In the process of looking into all of this, I also noticed that the Apple TV has recently added support for AirTunes as well. And so I'm going to see if I can borrow my friend's Apple TV and try to get the plug-in working with that too.
If anyone out there has purchased a new Airport Express with 802.11n and was thinking of using Remote Speakers output with it, send me an email or post a comment here with contact information. I'll send you a time-limited development version of the plug-in that should tide you over until I get a new release version cut.