According to recent publications Firefox had just crossed the 30% Market Share line. I still see every day websites that look bad on Firefox, and I find it pretty amazing that webmasters tend to ignore the trends and continue working for Microsoft only. I have actually never understood why web developers build IE-only websites, since developing sites for Firefox is 10 TIMES EASIER than doing it for IE.

Here is the graph as it looks today:

(Credit: Asa Dotzler (Data from StatCounter))