Tom Singer at MLB.com has a goo article on The graying of baseball. Singer points out that Jack McKeon at age 72 is the oldest major-league managerial hire ever, beating out Casey Stengel, hired by the Mets at age 71, by one year for the dubious distinction.
Indeed, this season has seen baseball match the all-time high for managers that are 60 years of age or over, six: McKeon (72), Alou (67), Robinson (67), Cox (62), Torre (62), and Torborg (61). By the end of the season, Lou Piniella (Aug. 28) and Jimy Williams (October 4), should join them in the 60-or-over crowd and a new "record" should be set.
Six senior-citizen managers also managed in 1960: Casey Stengel (Yankees), Charlie Grimm (Cubs), Chuck Dressen (Braves), Del Baker (Red Sox), Jimmy Dykes (Indians and Tigers), and Tom Sheehan (Giants).
It makes sense that with people living longer and being active longer in our society and with expansion adding to the ranks of active managers, that there would be more near-retirement-age team skippers. It's somewhat odd that the previous high came before expansion, actually.
However, given the dearth of successful managers past the age of 60, it may still be too grueling a job for an older gentleman and a number of these elder statesmen of the game, though successful as they now may be, may be forced into retirement in the coming years. We're sort of in uncharted territory here, so it's hard to know what will happen. Though someone breaking McKeon's new "record" may be hard to find for a few years.