What a wonderful series. I've said it before, but I'll say it again: if this is what kids are clamoring to read, then I have hope for the future. Not only are the morals good, but the storylines are preparing the readers for other literary works, including not only Greek and Roman mythology, but also such things as C. S. Lewis' "Narnia" and Tolkien's "Lord of the Rings."
Near the end of the third Potter book, Dumbledore (so much more than just an "old-man-as-mentor" archetype described by Jospeh Campbell) counsels Harry after Harry has mercifully spared a traitorous informer against the Potter family: "This is magic at its deepest, its most impenetrable, Harry. But trust me ... the time may come when you will be very glad you saved [his] life." Anyone who reads that, who has also read the Lord of the Rings, will recognize immediately the similarities to the conversation between Gandalf and Frodo at the door to Moria about Gollum. Kids who read Harry Potter are thus ready to be introduced to Lord of the Rings, and will recognize the motif in the same way.
The Potter books are simply stunning; I can't believe I waited this long to read them. The movies don't do them justice by half.
Incidentally, I have a guess about the Harry/Hermione relationship; I think it will mirror the Luke/Leia relationship. But who knows? ;-)