This is very interesting to me too. EastnWest, my son sounds close to the age of your son--he just turned 5 about 6 weeks ago. I have not pushed him to read AT ALL--my attitude has always been that he will learn when he's ready. He has an amazing vocabulary and is just a quirky kid. We recently had him tested and were told he is HG. Probably on the low end for these boards but high nonetheless.
My son just has not seemed all that interested in learning to read on his own yet. I think his attitude has been--"the things you can read to me are WAY more interesting than the things I could read to myself, so why bother." He is also an extreme perfectionist, and wants to quit trying when he comes to the first word he doesn't know or can't figure out easily.
My son is highly auditory, like Grinity described. He has been able to rhyme since he could talk. He thought it was a funny game when he was 18 months I would say a word and he would rhyme it (sometimes with a real word and sometimes a nonsense word). He didn't even know what he was doing but it was an impressive "party trick." Now if I spell words he will tell me what I spelled, but something between the visual "reading" and decoding is more of a struggle. We did have his vision tested at the request of his preschool b/c he rubs/blinks his eyes a lot but the opthamologist found nothing.
Anyway, I have been reading a lot more about giftedness since getting back testing results on my son and I'm always blown away by the kids that are reading at two. I mentioned this before on these boards and several people said that not all HG kids are early readers. It does make me wonder though how my son's abilities are going to develop and at what time and pace.
