This is one of the areas where heroku does a great job. It's very good at cloning apps, if you're using their addons(memcache, redis, etc.) it'll take care of provisioning new instances automatically. We use amazon rds but that's the only thing we have to setup if we want a new environment. Now that postgres is available on amazon we'll probably switch to that which will mean we can even use a cheapo heroku postgres instance for product demos etc.
With regards to setting up a company to do this, I'm not sure. A staging environment really needs to be as close as possible to production. Perhaps docker will become enough of a standard that it'll be easy to match production apps much easier in different clouds...
With regards to setting up a company to do this, I'm not sure. A staging environment really needs to be as close as possible to production. Perhaps docker will become enough of a standard that it'll be easy to match production apps much easier in different clouds...