We gave some serious thought to building a Java app. If you were to freeze the technology platforms as of today, there would be no question that we would go with a Java/open source development strategy. Java has some key pieces of technology that are difficult to replicate on a Microsoft platform. Java really is the best platform right now for large scale web development. The Hibernate object layer is powerful and I like the various Ajax framework options better. Java is the safe choice.
But we're making a technology decision that will shape our company for decades. So we're looking as much at upcoming features and technologies as we are at current capabilities. And this is where Microsoft starts to shine.