Sega and Nintendo revealed an exclusive deal for three titles starring Sonic the Hedgehog for Nintendo 3DS and Wii U - the first two, Sonic Lost World and Mario & Sonic at the Sochi 2014 Olympic Winter Games, have been revealed, but apparently both these two titles and a third unannounced title will see release before the end of the year.
German site Spindash have posted a German press release that clearly states that all three games included in the deal with see release this year - not within a year - but this year. Hopefully we'll learn more about the third title at E3. Time is ticking.
Update: Nintendo in Germany has clarified that only Sonic Lost World has been given a release date, while the other two games are TBA for now. This means we probably won't see all three games in 2013 after all. Oh well, translating is sometimes troublesome.