Hi Dex, MicroB is a seperate project by Nokia, Mozilla Fennec is a revival of an earlier project called Mozilla Mobile. When Nokia started with MicroB the Fennec project was not yet (re)born. Changes in MicroB are open source and backported when applicable. E.g. Gecko will receive improvements from all these projects. Mozilla and Nokia collaborate together, but each have different commercial priorities as well. The projects serve a different purpose. Fennec's primary platform is Maemo, but also ports for Windows Mobile are planned. Nokia has no interest to port MicroB to other platforms (but you are free to do so, the source is there). If you compare Fennec 1.0 betas with MicroB on N8x0 you also see very different way of using the browser, each having their own advantage and disadvantage depending on many factors. The Gecko-based browser on N900 and Fennec 1.0 betas are more alike. For example, because both assume finger-based touchscreen usage.