Hi David,
Right now we've got a bare-bones buildpack here:
There's just not a lot that a buildpack needs to do on Windows (at this point). I am planning on making further DEA modifications to allow you to write your buildpack scripts using Ruby, Powershell or bare-bones cmd. I figure I can look at file extension and/or the first line of the file to determine the type. Poor man's hashbang :-) Right now the DEA assumes that the buildpack scripts / process is all Ruby.
I also am planning on expanding the "start command" part of the buildpack / app manifest to allow you to specify IIS specific configuration. Not really sure how to do that, but it's on my radar.
I suspect we could combine buildpacks eventually by putting some OS / stack smarts in them. I don't recall off the top of my head if the stack is available while the BP is running.
Just FYI, DEA modifications to run on Windows and use this buildpack are here in the "ironfoundry" branch: