I'm not a Casper user, and so am unfamiliar with how items like installer pkgs/dmgs are stored and organized.
However, it looks to me like if it's possible it's going to be via the JAMF REST API:
POSTing packages, file uploads, policies etc.?
Sounds like with some work, you could remove a great deal of tedium of uploading packages and creating policies.
We are actually looking at doing some things with Varnish in the near future. Adding Jenkins may enhance things even further. Jenkins free guide download found here http://www.wakaleo.com/download-jenkins-the-definitive-guide
I'm curious, do the things you're planning to do with Varnish have anything to do with auto-packaging and deployment?
To the original post, I'm aware of a few Casper shops with client counts in the tens of thousands, and my impression as a non-Casper user is that the routine task of pushing application updates to clients involves several distinct steps. I would have to think that at least a few of these larger orgs are already doing this and just not talking about it.. ?