In an article at readwriteweb.com, They analyze the various services used by software start ups funded by YCombinator. (YCombinator is kind of a super-angel investor fund which funds small software start-up teams with small amounts of money to get them going before they get money from other sources). The full table on which the article is based shows that lots of services used by startups are cloud-based. For example, Google is the overwhelming choice for email host.
One interesting statistic is that although many apparently used amazon.com as their web host, the [SSL] certificate type of "*.heroku.com" shows that these startups are actually deploying their systems on the platform-as-a-service (PaaS) vendor heroku.com.