While everyone else is trying to be everywhere all the time, Mozilla at present does not think they need a Windows phone 7 presence.
During an interview with Softonic, Jay Sullivan, VP of Products at Mozilla Corporation said they were not a present thinking of Windows Phone 7.
At the moment we are focusing on Android in terms of the browser. For those other platforms we may do things like Firefox Home, so you can fire up any browser and get to your Firefox data. Weâ€™re not looking to bringing Firefox itself to Windows Phone 7 at this point.
While we understand the difficulty in getting an alternate rendering engine on Windows Phone 7 it is a bit disappointing not to see any commitment to bringing a FireFox Home-type app to Windows phone 7, which should generally be very simple to develop and support their brand on Windows Phone 7 also.
Read more at Softonic here.