Comment 8 for bug 724299

I can confirm this behavior; it's been the case for several weeks at least on natty and is still occurring as of 2011-03-11.

The gconf key seems to be getting set properly. On my system (allegedly configured to use Chromium as the default browser):

fader@cavil:~$ gconftool --get /desktop/gnome/url-handlers/http/command
/usr/bin/chromium-browser %s

If I click a URL or gnome-open one, I get Firefox. Interestingly, if I go to the Firefox preferences, it detects that it is not the default browser. Setting it as the default causes the gconf key to be updated:

fader@cavil:~$ gconftool --get /desktop/gnome/url-handlers/http/command
firefox %s

(As expected, URLs continue to open in Firefox at this point.)

Chrome recognizes that it is no longer the default browser and is happy to change the gconf key back for me:

fader@cavil:~$ gconftool --get /desktop/gnome/url-handlers/http/command
/usr/bin/chromium-browser %s

However, URLs are still opened by Firefox at this point.

I poked around in gconf a bit and just got more confused.

fader@cavil:~$ gconftool --get /desktop/gnome/applications/browser/exec
/usr/bin/chromium-browser

fader@cavil:~$ gconftool --get /desktop/gnome/url-handlers/ftp/command
firefox %s

(Admittedly, the FTP handler is likely to be unrelated to this directly. But it is interesting.)