Have you noticed that a lot of the Apple advertising and marketing is directed towards those that already have apple products?It's an interesting point. If various analysts are correct, most of the recent purchases of Apple products have simply been existing customers moving up to the newest device, not new customers coming into the fold.
I overheard a very telling conversation today where a colleague was lamenting that his teenage daughter wanted to get rid of her new iPhone 4 and get a "Droid" because all her friends were doing the same.
2) Figure out why it is working for Apple: can it work for you?
Apple seems to have retention down to a Science. For the most part, people who buy Apple stuff will continue to buy Apple stuff. If some of the typical pro-Apple opinions in this thread are any indication, people will overlook almost any amount of flaws in Apple so that they can continue buying Apple stuff. That's a powerful bit of marketing, but it may not be instructive to try and analyze and duplicate since most of that effect seems tied to Steve Jobs himself (we'll see if his transition out of the company changes this, even in the dark ages while he was gone there were still loyalists who clung to their ugly, underspecced and out-of-date Performas...heck there are still people who use their Amiga 500s daily).
It may be more instructive to see how:
1) Apple is losing non-computery people that they managed to bring into the fold, what's going wrong (based on the conversation I heard)?
2) How can they reverse this?
3) Where are they still growing, what are they doing right?