Several comments here indicate that this practice is outdated. I disagree strongly. Even in 2011 autoneg is flaky on many switches - in a recent shipment of ~10

Several comments here indicate that this practice is outdated. I disagree strongly. Even in 2011 autoneg is flaky on many switches - in a recent shipment of ~100 machines, ~5 of them autonegotiated to 100mbit instead of gigabit. And these are name-brand machines with name-brand switches. Forcing duplex and speed with ethtool is still relevant.