Register him an account for StackOverflow.com and Programmers.StackExchange.com
and get him into the habit of browsing different questions when he is bored. Start with the hot/most popular questions.
Also
Help him come up with a goal of something he wants to create that is slightly beyond his reach, a simple game, an app that can send a tweet? It has to be something that is exciting. This will help guide the topics he exposes himself to and provide him motivation through the tangible output he creates.
And
Where possible don't buy books in physical form if he works well with digital print, I am sure one of you has an android or iphone or blackberry or ipod touch? Get the ibooks or kindle app and buy digital versions.
Having to deal with a physical book slows the process of knowledge acquisition; the tools built into digital readers provide greatdigital readers provide many benefits to technical reading.
Note: as mentioned in the comments, there are drawbacks to digital vs printed books, so take this point with a grain of salt