On the PHPFog blog there's a recent post explaining their service in a bit more detail and how it provides the PHP applications out there with a huge amount of scalability that a traditional virtual server can't.

PHP Fog is a new type of hosting provider for PHP applications developers to build applications the good old-fashioned way but with easy scaling, reliability, speed, and easy deployment/management compared to traditional shared/dedicated hosting.

They look at a few situations where scalability can play a key role - traffic surge, growth leads to performance degradation and underutilized servers - and how the answers to these issues are best described as "scaling up", "scaling out" or scaling down", all things that more traditional hosting doesn't do well. Cloud-based platforms, like PHPFog (or Orchestra) can give you that high availability you need, so no matter the situation.

In this new article on the Zend Developer Zone, Wil Sinclair has made a "forecast" of sorts as to the role that PHP could be playing in cloud computing in the future.

There are three kinds of services that are commonly associated with the cloud: Software as a Service (SaaS), Platform as a Service (PaaS) and Infrastructure as a Service (IaaS). Software as a Service has gotten a lot of good press in the past few years, as Salesforce and the like have seen adoption from the smallest shops to the largest corporations.

He points to Platform as a Service as the most likely target for PHP (like the Google App Engine). He also points out some of the other providers for the other types (SaaS, IaaS) like Salesforce, Mosso, Amazon Web Services and Rackspace CloudServers. He digs into a bit more detail on the IaaS services, describing how they work (complete with a fun image) and how your application would fit inside.

On the Ibuildings techPortal today Vito Chin has posted a new article dealing with PHP and "the Cloud" - where the popular web language fits into the move towards cloud computing.

Cloud computing refers to the utilization of shared, elastic resources and processing power accessed via the Internet. In some ways, it hails the reversion to the golden age of time-sharing but with significant improvements to the distribution philosophies underlying the delivery infrastructure. [...] Cloud-based development involves in some sense, the outsourcing, of various parts of the application out of the server and into the cloud.

Included is an illustration of how an application would interact with the cloud and an example of working with the S3 service that Amazon offers. The example mentions both the normal services and something called the "elastic compute cloud" that lets you use remote services to run virtual instances of other operating systems.