Re-associate FireFox 3 with Thunderbird links

After upgrading to FireFox 3, I noticed that ThunderBird was no longer opening links in FireFox. Unfortunately, there are no Preference entries to modify how ThunderBird opens links, which means going into the Advanced Config Editor (the ThunderBird version of about:config). Just Another Tech Blog (among others) details how to configure ThunderBird to open links in FireFox. My problem? I had pointed ThunderBird to /usr/bin/firefox-2 when FF3 came out (I was still using FF2 at the time). FireFox 3, however, is located at /usr/bin/firefox.