GP and I wrote an article on "The Architecture Dimensions of the SaaS Ecosystem" for the International Association of Software Architects (IASA) Special SaaS Issue newsletter a few months ago.

In this article, we provided an overview on the market players in the SaaS ecosystem and described the application, consumption and hosting architecture concerns of the ISVs, enterprise consumers and SaaS hosters respectively.

You can download the IASA newsletter from here.