Sure, this may not be a proper Pokémon game, and right now it's only set for release in Japan, but the fact that a Nintendo product is coming to smartphones is a huge step for the company.
It's worth noting that the Pokémon series is developed by Game Freak and headed up by the Pokémon Company, so dabbling in iOS support with this franchise is a bit easier for Nintendo than say, Mario or Zelda, which are two franchises that the Big N holds a bit closer to home.
So what does all this mean? Will we see a fully fledged Pokémon game come to the iPhone? I sure hope so, but I'm certain it will all depend on how well the Pokédex is received. Please Nintendo, please make this happen! I would so love to play Pokémon Yellow or Gold on my phone!