No Chris, I haven't.  FF 3.x is just borked on the mac as far as extending it goes.
I wrote some scripts that would allow me to jump from the current open safari url to the same url in firefox (useful for testing) and that no longer works either.  There are a bunch of bug reports that have been logged at mozilla since the introduction of 3.0 and no-one seems to care.  Really doesn't bother me too much since I don't use it very often but for those who do it's a killer.  I typically use Safari and it's developer tools.

On Mon, Jul 20, 2009 at 2:01 PM, Christopher Suckling <suckling.list@googlemail.com> wrote:
On Sun, Jul 19, 2009 at 8:44 PM, Greg Newman<greg@20seven.org> wrote:

> Kieth, I've been working (in my spare time) on a applescript solution that's
> elegant.  When I get it finished and working I'll let everyone know.  I'm a
> Safari user but when it's done it will work with FF (or camino) too.
>

Greg,

I'd love to know if you've had any success with FF. As of 3.5, there is a
getURL object, but I've not been able to get it to work reliably, and,
regardless,
it still leaves FF as a rather second class citizen compared to Safari.

If it's of interest, you can find my (finally) rewritten suite of
scripts for org-protocol
here:

http://claviclaws.net/org/

Best wishes,

Christopher