Having met one of Xobni's co-founders recently and hearing more about Xobni's vision, I can tell you that they are not just planning to be a plug in for Outlook. Xobni Insight is a plug in for Outlook, but it is just a starting point for the company. They do want to expand into Yahoo and Gmail clients, various instant messenger clients and who knows what else to help organize your personal information. Give them some more time and I'm sure you'll be seeing more offerings before long.