Does it make for smart business for widget developers to put all of their eggs in one basket for a single social network? No, not when there isn't an established market leader in social networks, and not when the market is so immature.

Read the story of the MySpace and how it has grown from "only" few hundred thousands of users to over one hundred million. In the middle they switched from ColdFusion to ASP.NET. The scalability issues with web servers and databases are interesting to read.