Work is underway to get SVG support into Mozilla. Dean Jackson issued a call to arms for developers to work on the project.

Jackson wrote that the idea was to pursue a similar path to that of the MathML in Mozilla implementation:

Mozilla already has a whole heap of stuff to help with XML/DOM/CSS/Scripting, leaving most of the work in drawing the SVG on the screen in a platform independent manner.

If you are interested in helping out in any way (including writing code, QA, documentation, etc) please let me know. I've volunteered to organize the project.

Jeremy Lea responded, pointing to some efforts he had made getting SVG working in Mozilla, but had to stop due to time constraints.