Believe it or not, we first heard of SDXC nearly a year ago. Aside from a highly guarded chip spotted at CeBIT, though, we've yet to see any of those cards in the flesh. Thankfully for the impatient among us, it seems as if the SD Specification 4.0 is well on its way to being hammered out, with the maximum data transfer rate scooting up from 104MB/sec to 300MB/sec. The actual scheme will also be changing from parallel to serial, with an unspecified amount of pins (more than 9, though) assisting in the speed increase. We're also told that the external dimensions of the cards will remain the same, and that backwards compatibility is of the utmost importance. We're guessing that newer cards will be able to rely on parallel transfers when used on older readers, while newer readers will accept data via the serial scheme; unfortunately, the nitty-gritty details have yet to be made public, but we're hoping for a serious coming-out party at next year's CES.