I just discovered them on a message board while wasting time at work. They look really cool and get nothing but great reviews from the moms on the message board. The kids play with them for years. It doesn't look like the are available in many stores, but http://www.amazon.com/ sells them. They are pricy, but it sounds like they're worth it.
Here is another super cute, super expensive, toy that kids and parents love. Automoblox
The cars come apart and if you have multiple cars you can use the pieces and parts to build your own car creation. They are also available on www.amazon.com.
I'm sure Zack will have at least one of these two toys under the Christmas tree. Okay, so he'll probably get both. They are educational!
I thought I'd pass these along to other parents who hadn't seen them and like to start their Christmas shopping in July :)