My 3 year old son loves the PBS Kids show WordWorld, and they have a fun iPhone app (http://bit.ly/b4Kuen). It’s costs $1.99 and, although it’s not perfect and occasionally a little buggy, my boy is bananas for it. The show has taught him a lot of words and a lot about reading, and the app helps reinforce it, plus, like most iPhone apps, it does wonders for his hand/eye coordination. I wish there was a little more to the app, but that doesn’t seem to bother my son.

I’ll need to take a look at the apps you mention in the article. So many iPhone apps are such garbage it can be a real task to find the gems.