The first time I showed my iPhone to my two-year-old niece, I was amazed at how she knew exactly what to do with it. We were looking at photos (she has a lot of fun identifying family members) and she knew exactly how to swipe to get to the next one. And she was mesmerized by it — the familiar faces on the small glowing screen were utterly captivating. It won't be long before she'll be ready to conquer an iPad on her own, at which point we'll want to make sure we've implemented some common-sense hacks for adults who share their tablet before sharing the device with her.
I imagine that, as comfortable as I am around technology, my niece and everyone else who's currently a toddler will be a million times more at home with it. I started using computers at a relatively young age, but they've been surrounded by tablets and phones since before they were born. They are going to have an instinctive knowledge of how to use them.
Given all of that, it's important to make sure you're training your toddler right. Before letting them loose on your iPad, you'll want to put a few protections in place so they don't stumble onto something they shouldn't — and also so that they don't accidentally delete any apps or change your settings.