Regardless of how you slice it, 512GB is a lot of bytes. Sure, typical hard drives are comfortably in the terabyte-plus range, but in the fast-improving world of flash memory, this number is very much in the upper tiers. However! We're not talking SSDs here, no, Sandisk has just announced it'll be pushing out a 512GB SD card for all those outrageously high-definition video cameras and DSLRs.
The card itself will be a part of Sandisk's "Extreme Pro" range of SDHC / SDXC compatible gear and should deliver read and write speeds of 95MB/s and 90MB/s respectively. Otherwise, there's nothing particularly exciting about it specs-wise.
Oh, except it'll cost you $US799. Yep, that's $US1.56 per gigabyte.
Note that if you go hunting for it online, the card has two models numbers, depending on the region. For Australia, "SDSDXPA-512G-G46" is what you want, while in the US (where you might be able to get it cheaper) it's "SDSDXP-512G-A46". As TheNextWeb's Jackie Dove points out, B&H has it for pre-order for $US729, with shipping expected midway through next month.