MSN Virtual Earth has been around for a couple of months now. In the unlikely event that anyone has missed this, it provides a great mapping engine for satellite and roadmap style views. The bit I care about as a developer though is that we've really tried to make it a platform for building new applications, and so I wanted to link to places where you can find out more about the APIs.
Secondly, there's a community site called Via Virtual Earth that adds additional documentation as well as some great samples. Right now, you can find a Hurricane Rita tracking app, a photo map, a Windows Forms sample, and a Yahoo traffic data mapping, along with perhaps 25 others.
Anyway, if you haven't looked at this stuff, it would make for an interesting project, particularly given the competition that's running right now.