The reference is to a clause in the Federal Tax Code, number 401(k), which allows companies to deduct money from employee checks and direct it to a retirement account. This is advantageous to the employee, since the amount deducted from his pay does not count as income on his taxes that year, while the interests and dividends on the investment is sheltered from taxes until withdrawn, which increases the effictive return. In many ways it is like an IRA (Individual Retirement Account), but it allows more money to be sheltered.
There are issues. As JollyRoger says, some companies have taken advantage of the participants by making the compny stock the only investment available. When the company goes bankrupt, the people lose their retirement savings. This affects the highly paid people, the decision makers, much more severely than the hourly people, so it is rather uncommon.
The problem is that the whole 401(k) structure is a loophole. Its not a very big one really, but broadly available. Because of things like IRA's, the IRS has taken the position that they are good public policy, and has basically allowed them to exist hassle free. But, since it is a loophole, and not a law as such, there was no planning which went into the creation to protect the investors. It is because of this that the one company disaster cited above could take place. The disclosure requirements are almost non existant, and are based solely on customary and ordinary practices, rather than on code and regulation.
One thing that aggrevates me no end is that you must seperate from your employer to get access to the management of your money, which means that the options they give you are are there ever will be. Were it planned, there would be vesting periods, after which you could take the money and invest it anywhere.
All in all, it is one of those things that rich people pay their lawyers large emounts of money to find, that turns out to be useful to nearly everyone tha pays taxes. If you despise the concept of trickle down, here is a counterexample. The rich found it, but it benefits the middle class most. It is one of the no brainers in life. If they offer it to you, take it. The costs are small, and the payout, especially if you happen to be young and have little money, are big, huge even.
J