Microsoft announced Azure at the PDC yesterday, and it's got me thinking in all kinds of directions.

I've been an occasional visitor to StackOverflow.com since it launched a while ago. I can't say I've been an active participant - my reputation is only 271 at the time of writing, but even with my occasional visits I've noticed a theme that comes up in quite a few questions: does it matter whether I write efficient code? This manifests itself as people asking whether those "pure" computer-science topics like algorithmic complexity and computability are worth learning, and also in answers to many questions that were not obviously about performance or efficiency.

Right now, Microsoft seems not to have decided exactly how it will charge for host applications on Azure, or how it will charge for use of its hosted services, but it seems likely that the cost will be some function of resource usage: CPU time and storage space used, for example.

So, for people targeting that environment with their applications, there could be whole new reason to design efficient applications: it'll be cheaper to run. Ok, I guess that's always been true but it's often been somewhat hidden among the other costs of maintaining an application. If/when the business starts receiving bills from Microsoft quoting amounts of CPU, storage, and other resources consumed by your application, you could make yourself very popular by shaving a few percent off those bills :-)