The financial markets have their secular cycles. Technology has its S-curves of adoption. Problem is, it's impossible to tell when that S goes from under-performing little bottom coil to the roaring top of the lucrative cobra head. If you're baffled, have a look at these S curves and you'll know what I'm talking about.
Now, I'm making some large leaps and am most likely off on my history, but the distance from the Object-Oriented buzz of the late 80s to the SOA crescendo of 2004-2005 was a long time coming. The distance between the ASP model in the early 90s to the Utility Computing craze after the dot com bust is finally now turning into the full-throated scream of cloud computing. Seems to be everywhere now. Everyone's on some cloud or the other.
So much so that some major IT vendor is going to make a commercial using the old Rolling Stones anthem as the soundtrack.
So what's changed? Why now? Is cloud just the same old same old? There are a few critical things that have changed.
Reasons for the rise in cloud computing (IMHO)
1. technology advances have driven down the unit costs of:
1. set up
2. this makes the cloud computing business model viable (vendors can make money even if they are not at full capacity -- similar to less than full load trucking).
3. Browser technology is much much better (with AJAX and other related scripting, tools, and technologies)
4. Web and non-web programming languages and interfaces have improved -- so you can run the front end on a scripted language like python with a back end CICS or mainframe (for example).