IaaS, Heroku and the 2 minute Rails deploy
Devs hate dealing with infrastructure. They'd much rather code solutions than worry about whether the servers have been updated, a piece of software is there or the environment differs from what they have on their development boxes.
Amazon EC2 started it (though really you still need to manage the hardware), Google app engine (if you like python) followed, and Heroku made it seemingly effortless to deploy and run Rails apps. It's now following with pricing plans, both Shared and Dedicated that can handle production deployments (I love the pricing tier names : Blossom, Koi, Crane, Ronin, Fugu and Zilla... ;-) ). IaaS (Infrastructure as a Service) is now becoming the increasingly accepted standard for devs in both startup staging and business production.
Easy to use ? Haven't tried it myself yet (will post when I have), but this little howto from one of the boffins at github makes it sound like it's super easy peasy. Going to try it with one of the smaller apps I've got running to see how it runs. Will post impressions. You don't even need to use capistrano for the deploy (though I really love cap personally and think that's a downside.).