Oh yeah, didn't see it was May 23rd. Sorry about that!
In any case, it IS true. SEGA has had more then enough time to correct it, and it's been said repeatedly at this point that we already know about two games. Hell, that link i gave you had Kotaku confirming it directly from SEGA. It wasn't just a little tweet.
Well, believe what you want. You'll see soon enough I guess.
I doubt Nintendo was "hoodwinked". Nintendo will have known about the production of Mario & Sonic 2014 since the beginning. This is just being sold as a "three game deal" by PR because Mario and Sonic happens to be coming out at the same time SEGA is giving Nintendo two exclusive Sonics.
Regardless, we don't really know much about this deal, so there is not much more to say