What does QE2 mean for your investments?

Federal Reserve chief Ben Bernanke delivered just what financial markets were looking for last night. The Fed is planning to buy roughly $75bn of government bonds a month between now and the middle of next year. That's $600bn in total. Stocks went up, the dollar slipped back, yet gold didn't go haywire (although it's up again this morning). So what does it all mean for investors?