Rather than being a simple touchscreen-enabled port of the original click wheel game, the iPhone Song Summoner contains both Song Summoner and Song Summoner 2, which was never released due to Apple ending support for click wheel games.
If true, one would have to wonder why Apple is ending support for the format. New iPods aren’t due for another nine months but might Apple be preparing for the end of the click-wheel? Mini touches? It is all specualtion at this point but curious.