The oldest baby boomers have already made their transition into retirement, and the youngest are on their way. They now face the prospect of some well-deserved R&R after several decades in the workforce -- but poor financial planning could derail that for some.Baby boomers are on track to live longer than any generation before them, which means their dollars will have to stretch much further in retirement. But those who fail to plan for this may find their financial security in jeopardy at the time when they need it the most.