A cellphone is a lot like Los Angeles. People love to bitch about it, but they could never think of living without it. Now it seems that your kid might feel the same way. I saw this article yesterday about a company called Mobile Baby Toy. It's a pretty simple idea really You download a piece of software into your (mostly) Nokia cell phone and it turns your cell phone into a beeping, flashing toy for your kid to play with. I guess the point is to give your child something to distract them in a pinch if nothing else is handy, while at the same time preventing errant calls to foreign countries.
It's not for me (I rock a Treo 600), but for 9.95€ it might be worth it. Though my gut says teaching your kid that a cellphone is a toy probably isn't the best idea in the world. Unless you don't mind it in pieces all over the supermarket floor.