While most of the news in the enterprise SaaS space is often generated by Salesforce.com, another smaller but very interesting player is Etelos who offer a general-purpose multi-tenant application platform designed for the SMB market. Their strategy is to help those companies and the thousands of ISVs that serve them to have a fully hosted, scalable development platform for a variety of vertical business applications. They've been around for a few years and now have about 850 developers offering over 200 applications.
One example application was recently created by Etelos themselves: Etelos CRM for Google Apps. It's a composite CRM-type system that's delivered as a customized Google start page incorporating a number of their own modules to create a gadgetized contact, account, project, and task system. For Etolos developers they provide the source code for this as the starting point for other apps.
Overall it's an interesting evolution of the strategy Microsoft has successfully employed for years: cater to the many smaller independent developers out there building thousands of customized niche applications. Each app needs many of the same components, so the argument is we'll help you with those re-usable components and also take care of some of the dirty work like licensing, accounting and so on. These are also the types features and benefits that Salesforce.com's AppExchange provides. I spoke with CEO Danny Kolke and he pointed-out that one of their advantages is that customers can at any time opt to license and install their application on their own systems, so they are not restricted to only the hosted solution.