From infrastructure to the whole business, everything is now avaiable as a service. 1. Virtualization won the game. Costly to maintain a server and hire qualified HR. 2. Small to medium ISV can't compete (expertise, time, investment). 3. No one else will make the choices for you. Cloud omputing won't prevent you from screwing up your projects.
The focus is given on what's essential: the application, not on "how to host and monitor it". 1. The big picture is own by you, you know the blocks (db, app server, front end). 2. Scaling won't be guessed by the system, you have to configure the system so that you can monitor your app (Exceptional, Hoptoad, Errnot, ...)
1... without knowing it. Saas is new name for a very old and common thing actually... 2. So easy to set up that you will use it, nobody likes to setup servers (even using Chef and vagrant). 3. Give it a shot, it's risk free. You're the customer and can opt out if you prefer to spend time configuring your machines. 4. It's still growing and searching for new ideas. You can eat a part of the cake by building an awesome app and be partner with EY or Heroku.
Choose one of the best player: Heroku: VC funded * Blake Mizerany from sinatra EY: * Ezra Zygmuntowicz * Yehuda Katz * Carl Lerche...
Choose the vendor that will fulfill your requirement the best (incl. cost and time to market). You must be able to switch each component from the OS to the caching middleware, from Linux to Varnish and Toky Cabinet.