Recently, Firefox is very hot. But for developers, it may not be good. If your software, it is tightly combined with IE, using Bho or IE, etc. With Firefox users, support Two browsers are so late. This invisibly increases the burden. You may need to learn XUL, XPCOM / XPConnect.
There is also a good side, such as now your software supports two browsers, and the opponent only supports IE, then you have a lot of chips.
The influence of the two browsers on the developers is limited. Imagine how Linux and Windows accounted for 50% of the market. :)
