Pinkie: Twilight, you did a great job your first time around. I'm sure that my first time was just as wobbly and bobbly and crasharific as yours
Twilight: really?
Pinkie: No, but did I make you feel better?

This. It shows that Pinkie has trouble seeing things from others point of view, and doesn't quite understand their emotions. Plus I have a friend who has aspergers and she is so much like Pinkie Pie it's almost scary. From the bubbly hyper social personality, right down to the randomly breaking out in song.

As someone who actually has been diagnosed with Aspergers I can say she might have Aspergers.