Since Widlfire is written in Java it will mostly work on all platforms. However, I have noticed that there are a few cases where the configuration dialogs do not work on non-Windows platforms.
When I look at the source code I see that you have lines of the form:
Runtime.getRuntime().exec("cmd.exe/C start "+url.replaceAll("&", "\"&\""));
This code will clearly only work on windows since cmd.exe is a windows specific executable. However, it would be easy to make this work on all platforms by using the org.eclipse.swt.program.Program object where the above line would become