After upgrading to Feisty, any attempt to use the Ruby-Gnome2 Gtkmozembed bindings fails with:

$ ruby ruby-gecko.rb 
ruby-gecko.rb:203: [BUG] Segmentation fault
ruby 1.8.5 (2006-08-25) [i486-linux]

Aborted (core dumped)

After an hour of searching online, I discover that (a) the problem isn’t limited to Ruby, and (b) the fix is quite simple:

$ export LD_LIBRARY_PATH=/usr/lib/firefox

It’s things like this that make you crazy.