Lighthouse2bugzilla is a project mainly written in PHP, it's free.
A couple of scripts to home move bugs from LightHouse to Bugzilla
These scripts work in conjunction to move export bugs from LightHouse and import them into Bugzilla. The export script creates a JSON file. The import script creates a SQL file.
lighthouse_dumper.rb pulls gunk outta lighthouse using their web api, resulting in a json database of your bugs
import.php pushes that gunk into bugzilla
Much has to be customized with the scripts.
Good luck.
CAVEATES/BUGS