They've gone from $700 to $500 because of the possible fiscal cliff, you silly. They have been one of THE most-widely held and liquid stocks around, making up an absurd 4% of the NASDAQ or something like that. So when everyone with any financial savvy wants to lock in profits at a known-favorable tax rate what stock do you suppose sees the most downward (selling) pressure? AAPL. Makes perfect sense to me. "Let's see, I can take a profit now at 15% tax today or wait and perhaps get taxed as ordinary income (30+% for most investors)."
Stocks are generally valued as some multiple of their forward earning expectation, the P/E or PE ratio. There are no successful profitable growing tech stocks that naturally trade at 12x earnings. Oh wait, AAPL does. You're an extreme doubter if you think a stock that habitually sold at a PE of 30 to 40 now belongs at 12 or less. Even with the loss of Steve Jobs 15 is more like the natural low value (IMO) and I do expect AAPL price to at least exceed $800 after the next earnings report.
Gone from leaders to followers? I'm an Apple fan (though I do not own a Mac) and even I don't claim they were leaders most of the time. They just did many important things better. They still are doing enough things well, at least enough for you doubters to not hold your breath waiting for them to fail. Read reports about iPhone sales in China lately (today)? Apple is laughing all the way to the bank.