A quick heads up to those shooting with the Nikon D3, (this presumably effects the other Nikons too?)…If you are shooting with Image Authentication turned on, the buffer clearance times are increased. With my Extreme IV card it took an extra 10 seconds to dump a full buffer to the card.
Despite it being mentioned in one spot in the manual (but not in the image authentication section) most people I have talked to were unaware of this and as it could mean missing shots (especially for sports shooters) it is worth spreading the word.
This post on Nikon D3 Image Authentication and Buffer Clearance Issues is by UK based photographer and Nikon D3 shooter Richard Costin.