In case the 20Mbps sustained read/write speed of SanDisk's Extreme III memory cards is too slow for you--despite the fact that most cameras can't even write that fast--the company recently announced the Extreme IV line of flash memory cards, which is rated for a sustained read/write speed of 40Mbps (a.k.a. 266X). The line launches this week with 2GB ($160), 4GB ($320), and 8GB ($640) CompactFlash cards, though SD cards will likely follow eventually. In case you don't like life in the fast lane, SanDisk will continue to make and market both the Extreme III and Ultra II lines.
Currently, only a couple of medium-format digital backs can write fast enough to really take advantage of these new cards, though future pro-level dSLRs will probably take advantage of the increased speed at some point. Also, since no current card readers can keep up with these new cards, SanDisk has created a new Extreme card reader, available in two versions: FireWire 800/400 ($80) and USB 2.0 ($25). Initially, the FireWire reader will have only one slot, for CompactFlash cards, but a future version is in the works with a second slot that will accept SD as well as Memory Stick Pro and Pro Duo cards. The USB 2.0 reader will have two slots at launch next month and will also accept CF, SD, and MS Pro and Pro Duo cards. While the cards and readers will be available separately, SanDisk will also sell two bundles: a 2GB Extreme IV card with an Extreme card reader ($240) and a 4GB Extreme IV card with an Extreme card reader ($400).
As they did with Extreme III cards at launch, SanDisk is marketing Extreme IV cards to professional photographers, though that doesn't mean nonpros won't buy them. In fact, at the press conference to announce the new cards, a SanDisk spokesperson noted that plenty of nonpros have been buying Extreme III cards. This might have something to do with the fact that Extreme III cards--and now Extreme IV cards as well--are made to function across a temperature range of negative-13 to positive-185 degrees Fahrenheit, come with RescuePro recovery software, and have a lifetime warranty. Or, maybe people just want to think that their photos are just as extreme as their memory cards.