With most micro four-thirds/interchangeable lens cameras and DSLRs now shooting 1080p HD videos plus stills in RAW format, and capturing more frames-per-second rate in burst mode, no wonder memory cards (and standards) need to up their write speeds and storage capacity to keep up. SanDisk's newest SDXC cards (full size and micro) offer the fastest write speeds on the market right now thanks to its Ultra High Speed architecture, but will only work with a limited number of devices as it is not yet a widely adopted standard. (SDXC cards will NOT work in SD slots/devices for example: see this chart for details.)
Photography enthusiasts with relatively up-to-date high-end cameras and camcorders (2010 or later) should be compatible with SanDisk's 64 GB Extreme Pro SDXC UHS-I memory cards, as those are really the devices that this level of memory card is built for. It offers UHS Speed Class 1 writing up to 95 MB per second, so it's ideal for full HD and long recordings and maximizing your camera's fps in continuous shooting, according to the SD Association. But this kind of speed and capacity won't come cheap: $499.99 for the 64 GB, which is in-line with a similar card from Kingston per SlashGear.
SanDisk's 64 GB Mobile Ultra microSDXC memory card faces an even greater challenge than the Extreme Pro because most devices on the market now that use micro memory cards -- smartphones, MP3 players and tablets -- are not microSDXC-compliant. For those that include a memory card slot at all, they tend to read microSD and microSDHC cards and top out at 32 GB in additional capacity. Until microSDXC becomes more ubiquitous in gadgets, I don't see a need for a micro memory card that offers UHS-based Class 6 write speeds capable of writing 30 MB per second at the moment. I also wonder whether devices originally designed to accept 32 GB cards will recognize the additional capacity. If you like to be a gadget guinea pig and are deep pocketed, feel free to nab one of these 64 GB microSDXC cards from SanDisk for $219.99.
You can order both cards from SanDisk's website right now, or wait a month until they land in a retail store near you. Let us know how you like them. But you should definitely google your product's compatibility with the SDXC format before proceeding.