As the Cloud Market continues to take shape, many of the Cloud Providers have chosen to provide combinations of PaaS, SaaS, and IaaS. The reasoning behind this is that the market continues to be uncertain and probably will remain uncertain into the foreseeable future.
Why is the market uncertain?
Because different businesses have different demands and requirements. Mix this with the fact that developers are using the Cloud for portions of both public and private applications and you end up with no reasonable single answer to point to. Enter different types of cloud services for different businesses and business requirements.
So who are the primary players?
The larger players are offering at least two of the three service types and include:
IaaS includes offerings such as EC2 and S3
PaaS covers SimpleDB, RDB, and MP
PaaS with the Google AppEngine
SaaS under a suite Google Apps (Business Edition)
IaaS covered by Azure VMs (Service is estimated to be available in March of 2010)
PaaS includes Azure SQL Server and Others
SaaS includes MS Office Online
IaaS through Terremark
PaaS through SpringSource CloudFoundry
SaaS through VMware GO
(VMware doesn't necessarily provide these services directly, but does profit from them all)
By spreading their bets across all of these platforms, the Cloud Vendors are allowing the market to drag them to where and how it wants services. This is a good plan from the perspective of easily meeting the right market demands, however it may be difficult to provide good market differentiation in the long term. Over time, most people will be more concerned with PaaS and SaaS offerings from the consumer side. On the business side, assuming that Hybrid Clouds are the preferred deployment of cloud technology, IaaS and PaaS will weigh in more heavily as businesses need to invest in these areas to provide solid SaaS to business consumers internally to their organizations.
Uncertainty in the above prediction is also leading to fragmentation in each of the companies strategies. None of them want to spend money on a service or technology that isn't going to lead to money, whether directly or indirectly. On the flip side, none of these companies want to be driven or dominated by a competitor's technology or product. So their only choice is to spread their bets across as many of these solutions as possible and wait to see which becomes predominant. And then, they can focus more time and money on the winning solution.