Here a good recap on some of the new mutual funds offered to help with income.  Fortune looks at "income replacement" and "managed payout" funds.

Fidelity is offering 14 of what it calls Income Replacement funds. Unlike most mutual funds, they are designed to liquidate at specific dates: every two years from 2016 to 2042. The idea is for your money, plus investment gains, to be returned to you in monthly installments over the life of the fund. The portfolios invest in 15 other Fidelity funds, including 100 Index, International Discovery, and Total Bond. Early on, the funds will be managed for growth with a greater emphasis on stocks. The asset allocation will become more conservative as the fund nears its end date.

While the prospect of monthly income is appealing, you can't be sure how big those payments will be. The dollar amount will be set each year, based on a target rate and the fund's performance during the previous 12 months. If the fund has notched big investment gains, the payment may be larger. If it has a bad year, the payment may be smaller.

Vanguard is taking a different tack with its Managed Payout funds, launched last month, which are modeled on university endowments. Like endowments, these funds aim to leave the principal intact; they have no end dates and look to broader asset allocation to boost returns. Investors can choose from three portfolios: Growth Focus seeks to increase investors' principal while providing a modest payout; Distribution aims to preserve principal while maximizing the payout; and Growth and Distribution will try to strike a balance between the two.