You mean Apple's "R&D department", clearly not the industrie's.
R&D spending 2011:
Apple 2.4 bln
Microsoft 8.7 bln
Samsung 9.3 bln
To name a few. Once you combine the numbers of all the other players like Intel, NVIDIA, AMD, HP, Dell etc., Apple basically has no R&D.
2.4 bln is a joke in context of revenue/profit, not only compared to other tech companies. As other's have stated: Apple only assembles hardware components, benefiting from technologies others have researched and developed. My guess is that Apple's "R&D" budget is limited to design. They should triple their R&D budget and spend it on OS X.