If you're interested in Preon, then you may want to check out this blog, comparing an Erlang bit syntax example and Preon:
This blog post compares Google Protocol Buffers to Preon. They are similar, but different, and address different needs.
http://blog.flotsam.nl/2009/01/preon-versus-google-protocol-buffers.html
I uploaded a first snapshot distribution a minute ago. Easier to get started with this then having to download and manually build everything yourself.
There will be more uploads in the next couple of weeks. I intend to have at least the samples included as well.
Preon got presented at J-Fall, the Dutch Java User Group. Find the slides here: http://www.slideshare.net/springerw/preon-jfall-2008-presentation-746831