Sorry if I am just really dense, but I read the Top 10 Eclipse Kepler Features and I see Orion at #1. It claims to run all in the browser. I find it really interesting, but it looks like a completely separate tool. Am I wrong?
You are not wrong. Eclipse Foundation has grown beyond its initial IDE roots. In addition to the desktop IDE and IDE components, it also plays host to a number of frameworks. Orion is a browser-based development environment, entirely separate from Eclipse the desktop IDE. The only unifying aspect is that the project is hosted by Eclipse Foundation.