Cal Henderson, the lead developer of Flickr, recently revealed that they deploy new builds up to every half hour.

Support lightweight programming models that allow for loosely coupled systems. The complexity of the corporate-sponsored web services stack is designed to enable tight coupling. While this is necessary in many cases, many of the most interesting applications can indeed remain loosely coupled, and even fragile. The Web 2.0 mindset is very different from the traditional IT mindset! Think syndication, not coordination. Simple web services, like RSS and REST-based web services, are about syndicating data outwards, not controlling what happens when it gets to the other end of the connection. This idea is fundamental to the internet itself, a reflection of what is known as the end-to-end principle. Design for "hackability" and remixability. Systems like the original web, RSS, and AJAX all have this in common: the barriers to re-use are extremely low. Much of the useful software is actually open source, but even when it isn't, there is little in the way of intellectual property protection. The web browser's "View Source" option made it possible for any user to copy any other user's web page; RSS was designed to empower the user to view the content he or she wants, when it's wanted, not at the behest of the information provider; the most successful web services are those that have been easiest to take in new directions unimagined by their creators. The phrase "some rights reserved," which was popularized by the Creative Commons to contrast with the more typical "all rights reserved," is a useful guidepost.