I tried System Settings -> Details -> Default Applications -> Web but it's not listed as a web browser.
I also tried using update-alternatives, and it's listed there, but setting this doesn't seem to change anything--when I try
gnome-open http://www.something.com it still opens with firefox.
I also tried changing the gconf settings for /desktop/gnome/url-handlers/ but that doesn't seem to stick.
What can I do to make luakit my default browser?