It appears that I was right after all: the D300 did need an update for the 800mm f/5.6 lens. Today Nikon released firmware updates: v1.11 for the D300, v1.02 for the D300s, and v1.04 for the D700. All three updates list the 800mm lens support as the only change. These updates come about 45 days after the 800mm lens updates for the D4, D600, and D800 and after the 800mm was readily available. Fortunately, this was mostly an EXIF data change, but it does bring up something that is a little concerning: previous generation body owners were penalized a bit by the timing here. Given how prevalent the bodies in question are, I wouldn't want to see updates in the future slip any further in timing from the current cameras.