A reference platform is certainly critical, and IMO we should probably follow the standards that the Linux Standards Base Project is establishing.
Standards seem to only work when people start using them, and since some of the heavy Linux distros are buying in it would be great to be able to take advantage of common file arrangements.
LSB discussion continued here. Is there anything in LSB that sheds light on the /web stuff? The only thing I saw in a quick scan seemed to imply that we should put everything in /var/opt/package.