I'm a firm believer in cloud computing.
Yes, cloud is right at the peak of inflated expectations, but if you've been around long enough, you've seen this happen with Client/Server, Y2K and Web 2.0, to name just a few examples. The fundamental concepts of cloud are sound, the technology will catch up with the vision, and cloud will become an integral part of mainstream IT.
But cloud computing not only changes the way we consume computing resources, it also presents a sea change to many marketers.
Most cloud vendors make it real easy to onboard - just sign in and you're good to go. No need to ask your IT to set up a new server, no need to install any software, no need to (and usually no way) to embark on complex customization projects. Whether you market IaaS, PaaS, SaaS, or any other Gartner-oriented-cloud-acronym, remember that the last "S" stands for "Service". It is incredibly easy to start consuming a service, but it is equally easy to stop, or switch to another provider.
When I joined Zend a couple of years ago we used a paid web analytics service from FireClick. It was complicated, slow and buggy. We decided to check out Google Analytics, and realized it could easily do what we wanted, and for an attractive cost of zero. A few web page updates later and we were up and running with Google Analytics.
If your business is a cloud-based service, you just can't afford to slip. Your service needs to be unreasonably good. If you head marketing for a cloud-based service, remember it's not just about leads and conversions. It's about delivering great value to your users day in day out.