Pharmaceutical giant Merck announced this morning that it will pay more than $41 billion to acquire Schering-Plough. Merck is making the move as the drug industry faces massive revenue and profit shortfalls in coming years as cheaper, generic drugs eat away at some of their most profitable drug franchises. Merck and Schering-Plough already conduct business together, co-marketing the cholesterol drug Zetia and Vytorin, which combines Zetia with Merck’s cholesterol drug Zocor. “W...