I think Gengo has the best approach in dealing with multilingual content as it separates language data from the regular WP tables and mostly because it uses different posts for each language (unlike qTranslate, Polyglot, etc.)
It worked well with WP 2.3 but there are some quite nasty bugs with WP 2.7 and unfortunately development of the plugin is somewhat stuck for now.
But as I said Gengo's approach is definitely better.