Annuities Inside a 401(k)?

It seems Metlife and Prudential Financial and some other insurance companies are designing annuity products that go inside a 401(k) plan. These are deferred annuities that will pay an income stream to the 401(k) owner once they retire (which is similar to a pension plan).

I don't have a problem with this as long as they keep the fees low and waive the surrender charges. Just make sure you read the fine print.