it finally happened. A mere 2 months later than first advertised. When he came back from his dad's this morning, the tooth was hanging on by not much, and sure enough, when I picked him up from school he greeted me with a closed-lip smile. It had fallen out during the morning.
In this pic he is holding the letter to the tooth fairy that he wrote, which you can see in close up on Flickr, should you so desire.