That was enough of a sales pitch for me! I downloaded Letter School immediately ($2.99) on MY ipad, and can't wait to share this with our EC teachers at school! The app starts out where a mere touch will produce a letter or number, and progresses to where the child draws the item (upper case, lower case, or number) on his own. Each phase has animations as a reward----this is what our boy loved.
If you want to read a review, here's one by the Ultimate Autism Guide.
Here is also a video demo.