The net result doesn't always have to be zero. Consider advertising business goods and services in a business application (CRM, content management etc…). If you advertise those goods and services, you're adding something of value to the application users and are adding money to the pot and not taking it away. The goal of Etelos Ad Serve is to provide application users and developers a way to add this value.
I wanted to also note a product from Etelos, Etelos CRM for Netvibes. It's a gadgetized CRM suite that we've integrated into the Netvibes customizable homepage.
It has the ability to sync w/Gmail or Outlook, as well as manage projects, tasks, appointments etc…
I think Netvibes has the ability to be a viable business tool because of its accessibility and customization. People work better when they enjoy the tools they use and to have "Personal" stuff in the same place as their work stuff helps productivity.