It's possible they'll announce changes to their pricing, bundles or they'll announce release dates for Europe. I think that's much more likely than any new game announcement.
Perhaps they'll announce a NSMB Wii bundle for Europe? Or black Wii for Europe? Perhaps new DSL/DSi bundles?
European launch details for the Wii were announced at a similar event 3 years ago. In fact it'll be nearly exactly 3 years ago.