Alicia H. Munnell of the Center For Retirement Research at Boston College has written a number of research reports regarding retirement trends.  The Boston Globe provides a recent interview.

"Individuals can control two things: how long they work and how much they save. A couple more years of working makes a lot of difference. You're earning income, you're letting your 401(k) continue to grow, and you're shortening the period over which you have to support yourself. So at least get to 65. Then, in terms of saving, you always hear these days that people have to decide whether to pay for their children's education or put money into 401(k)s. Be selfish. In the end, your children will be happier with some student loans than with your living with them."