I've just been reviewing the MEDC internationalization session (covers Windows CE and Windows Mobile) - there are some interesting facts, did you know that only 8% of the world population speak English ? (5% native, 3% as a second language) - I'm surprised that more developers don't get involved with localizing (or globalizing) their applications or operating system images.
Both Windows CE and Windows XP Embedded are UNICODE based operating systems, and both support MUI (Multi-Lingual User Interface).
Some resources to get you started thinking about localized/globalized applications.
There's also content in the Windows CE documentation that covers MUI development.