Based on my research for multilingual SEO, accents in metadata may not be something people want to preserve (for instance, see this seomoz presentation on foreign language metadata). For this purpose, we've decided to use the transliteration project to clean all the accents out of the URLs.

Right now, we're doing this at the theme layer by overriding theme_metatag and theme_metatag_dc to transliterate. It would be great to have this as a checkbox option somewhere as part of the metatag module or perhaps the transliteration module itself?