If you're not ready to retire you shouldn't worry too much about the market. I'm not an analyst but I see these as mere corrections. If you're a day trader -- yes. Hedge funds are in trouble and some of the mortgage companies that overloaded on subprime (bad credit) loans are in trouble as well.
I am not worried about the market 'cause I'm not ready to retire and don't care about age 65. I want to retire when there's enough cash in the bank. My timeline is 60 at the latest. 401K is in aggressive stocks and mutual funds are at dollar cost averaging (putting in the same amount of money per month regardless of price). For those of you in your twenties, this is highly suggested. Sure, you may have student loans, credit card debt due to the wonderful salary at the commuters but make yourself one of your bills and put your name in front of everyone else. It looks like it's impossible early on but when that little nest egg starts acumulating that compounding interest you'll be amazed. Don't touch it and let it grow. I only share with you some of the things I am doing to give you ideas. Trust me, they work. At the ripe old age of 18 it was burned into my mind to do this. Twenty years later it's starting to show some nice numbers.
Good Luck!