This was suggested awhile ago, but haven't heard anything about it in a while.
This has been started as part of the ongoing improvement to the Prefs Kit (which provides Snarl’s user interface).
AdminChris P (Admin, Full Phat Products) commented
Ok, so there is progress on this happening behind the scenes. One of my other projects (Desktopia) is currently piloting a modified Prefs Kit which allows for localisation which, if successful, will be rolled into Snarl. Please keep voting for this feature!
Add support for spetial characters such as á é í ó ú ñ.