With HD video and ultra high-res digital stills putting more strain than ever on memory capacity, it's not surprising that the SD Association, the folks who develop specifications for the SD/SDHC memory format, have been working on a forward-looking, high-speed/high-capacity standard.
The result of this development, SDXC ("eXtended Capacity"), accomodates memory card capacities up to 2TB. For the uniniated, that's a full 2000GB. To put that number in context, a modern professional DSLR would be able to store about 4000 raw files on a 2TB card.
In truth, the new spec, which retains the same physical interface shared with its SD and SDHC predecessors, doesn't actually add theoretical capacity to the current SDHC format (which already has a theoretical, though as yet not even close to actualized, capacity of 2TB). What it does seem to do, however, is provide some formatting standardization (courtesy of Microsoft's exFAT file system) for the extremely high-capacity cards that are sure to come in the not-so-distant future.
To deal with exponential increases in storage capacity, the new spec also provides maximum data transfer speeds of up to 104 megabytes per second as outlined today, with future planned support for up to 300 MB/s. According to a statement from the SD Association filed today at CES, the current SDHC spec will be revised to benefit from these speed increases as well.
SD variants have become the standard of choice not only for the majority of digicams, but for camcorders, game consoles, and portable multimedia devices as well. While we don't know of any actual products in the works using the SDXC standard, with such broad appeal, it probably won't be long – a year or two at most – before manufacturers begin implementing the new standard in a retail-ready form.