Target-date retirement funds are designed to automatically shift investors' portfolios to less risky assets as they age. You name your retirement year, and the fund managers change the stock and bond allocation inside the fund to an appropriate risk level for your age, in theory getting a bit more conservative as you approach your ideal retirement date.

Almost 80 percent of large U.S. plan sponsors offered target funds as an investment option through their 401(k) plans in 2007, up from 60 percent in 2006, according to research by consulting firm Greenwich Associates. And even if you don't sign up, you could find yourself automatically enrolled in them unless you specifically opt out. "About 40 percent of funds that have adopted automatic enrollment use target retirement date funds as their default, compared with about a third using money market funds," says Greenwich Associates consultant Rodger Smith.

Unexpected expenses like medical bills or a death in the family can happen to anyone. And mortgage payments and credit card balances can creep up on you. When you're strapped for cash, the amount you've accumulated in your retirement accounts can look mighty tempting. And it's easy to pay the fee and borrow some cash from your retirement stash.

Some 27 percent of employees planning to retire have withdrawn funds early from retirement investments, according to a recent Wall Street Journal Online/Harris Interactive online survey. The reasons for withdrawing funds before retirement include (with share of all employees who have tapped accounts as a result):

Target-date funds are supposed to make saving for retirement easier by offering a one-shot, premixed portfolio that grows conservative as the years pass. All investors need to do is select an anticipated retirement date and voilà! Investment professionals handle the legwork, which includes allocating money to stocks and bonds and adjusting the portfolio to lean more heavily toward bonds as the target date nears.

Dear Alpha Consumer,

Do you know if my biweekly 401(k) contribution (on my paydays) is invested based on the market price of mutual funds at the beginning of the day or the end of the day?   I know that normally one shouldn't be concerned about such things, but when the market swings up or down by 7 percent on a given day, it can make a difference.

When the market ends up 9 percent one day and down 5 percent the next, it's hard not to be concerned about the timing of investments. I asked Fidelity, the country's largest retirement plan administrator, when, exactly, 401(k) money from paychecks gets put into the market.

I hate to use the "S" word, but the American government would never do something as, well, socialist as seize private pension funds, right? This is exactly what cash-strapped Argentina just did in the name of protecting workers' retirement accounts (Efharisto, Fausta's Blog). Now, even Uncle Sam isn't that stupid, but some Democrats might try something almost as loopy: kill 401(k) plans.

House Democrats recently invited Teresa Ghilarducci, a professor at the New School of Social Research, to testify before a subcommittee on her idea to eliminate the preferential tax treatment of the popular retirement plans. In place of 401(k) plans, she would have workers transfer their dough into government-created "guaranteed retirement accounts" for every worker. The government would deposit $600 (inflation indexed) every year into the GRAs. Each worker would also have to save 5 percent of pay into the accounts, to which the government would pay a measly 3 percent return. Rep. Jim McDermott, a Democrat from Washington and chairman of the House Ways and Means Committee's Subcommittee on Income Security and Family Support, said that since "the savings rate isn't going up for the investment of $80 billion [in 401(k) tax breaks], we have to start to think about whether or not we want to continue to invest that $80 billion for a policy that's not generating what we now say it should."

Good news for socially conscious investors: Greener 401(k) investment options are on the way. Currently, only one fifth of employees have access to socially responsible investing funds, according to this story. But survey data from the Social Investment Forum revealed that 60 percent of all plan sponsors anticipate adding SRI funds by 2010. (Currently, healthcare and government agencies are the most likely to offer SRI options, and most are funds from Calvert or Domini.)

What is SRI exactly? Funds that tout this philosophy typically invest according to social and environmental guidelines. For example, they may invest only in companies with sustainable business practices or with good environmental track records. But lumping all "green" or SRI funds together would be like ignoring the difference between vegetarians and vegans. As Morningstar points out, some green funds will own companies with human rights, labor, or environmental issues that might fail the screens of others.

There's more to the 401(k) business than you may think. According to CNNMoney's "The Mole," administering a 401(k) plan is expensive, what with record keeping and compliance costs. As a result, some administrators offer low-cost plans to employers that are loaded with expensive mutual fund options. If this is the case at your job, the Mole suggests approaching your employer about changing 401(k) providers and otherwise opening an IRA (after you take advantage of any matching funds offered by your employer).

But how do you know if your 401(k) is subpar? Jeremy at GenerationXFinance, who works as a retirement planning specialist, provides a couple of red flags to help you determine if you're in a lousy plan:

You might expect the nation's largest companies to offer 401(k) plans with low fees, especially since these firms most likely qualify for low-cost institutional share classes of mutual funds (the cost is low because institutional investors buy shares in large blocks). But that's not always so.

Wal-Mart, the country's largest employer, is facing a lawsuit that claims the company invested in expensive mutual funds instead of lower-cost alternatives, reports Financial Week.