About PaaS and SaaS
Introduction to PaaSfrom Wikipedia, it describes the definition of PaaS and its key characteristics, types, factors driving adoption and factors inhibiting adoption.
Introduction to SaaS from Wikipedia.
Introduction to IaaS from Wikipedia.
A discussion about the costs of PaaS, it compares the costs between two different implementations: running an EC2 instance to satisfy the server needs and getting a commodity managed server through ServerBeach.
Another discussion about costs of cloud computing
A article discusses the relations between SaaS, PaaS and IaaS.
8. Some earlier discussion about SaaS and PaaS.
PaaS, more than SaaS, July 2007
SaaS out, PaaS in, July 2007
First SaaS, now PaaS, April 2008