The SD Card Association has unveiled a 2 Terabyte capacity microSD  card spec (SDXC) [InformationWeek article]. The specification uses the exFAT file system (FAT64).  Recently, SanDisk trumpeted drastic improvement in flash write speed.  Granted, the drastic speed boost will come to market long before the SDXC spec is maxed out. Imagine the applications for carrying…