As you can see from the table above, Apple's outstanding shares (shares owned by people/companies that aren't Apple) have been going down for a few years now. This means that Apple is buying their own stock. When Apple buys their own stock, that stock pretty much goes away, and the total number of shares available to buy decreases for people/companies that aren't Apple.
As economics 101 taught us, when supply goes down, demand goes up. When the demand goes up, the price goes up. Since Apple is decreasing their stock supply, the demand for their stock will go up (as long as they keep making money), and therefore the price of their stock will go up.
I personally own Apple stock and after doing my own analysis and research, I am probably going to buy more. Apple is also a product I personally use, and it's a fun stock to follow compared to other stocks I own.
Looks like the next earnings report will come out on February 1st - http://investor.apple.com/. I will check back to let you know if Apple has continued to buy back their own shares.