If your app (or your framework) runs on Plack/PSGI you have a wide choice of server implementations. It will work under mod_perl, FastCGI and numerous other server environments.

Indeed if you write an app to run on DotCloud; you can also run the same app on your laptop, Phenona, any other server -- etc etc.

As someone else said (more politely), you'd have to be nuts to do an HTTP app now and not take advantage of it.