I'm experiencing this issue also, both with Chromium and Google Chrome. After installing the .deb package, I can use the Unity search or the Applications menu to launch Chromium. Either way, there doesn't seem to be a way to pin to the side-menu. Right-clicking provides the non-verbose name of the application - "Chromium-browser", and the only context option is "Quit". I'm using an HP Mini with an up-to-date UNE 10.10 from the final installer image.