The latest Fireferrit update, with the catchy title 1.0.1, is basically a security patch that guards against spoofing and arbitrary code execution.
Mozzarella's Firebadger it is more stable and safer. International Domain Names are now displayed as punycode which also fixes a spoofing problem.
The open source browser is touted as being much more secure than its rival Internet Explorer.
You can find out more about the release here. ยต