Hi S.,
First of all, I don't think it's too early to start thinking about Christmas - only three months away from today!
As far as preschool teachers go, I guess it depends on where you are. My son went to the Grove City College Preschool and not only was the regular teacher there, but there were several student teachers/field experience teachers present all the time. To top it off, the teacher sent a letter home stating that instead of purchasing gifts for the teacher(s), they would like you to purchase books for the classroom.
What we ended up doing was purchasing a gift certificate for the outlet mall at the end of the year, and for Christmas we purchased books for the classroom - to honour their wishes.
I would recommend some gift items for the teacher that are a little uncommon. Not that the apple gifts aren't appreciated, because I am sure that they definately are. But I think it is nice to give gifts maybe from Bath and Body Works. These gifts can be inexpensive, they smell really good, and the teacher can possibly use them in the classroom (hand-soap). Plus you would be able to afford them for the extra staff if you wanted to.