The new SDHC and SDXC cards will be available in 16 GB, 32 GB, and 64 GB designs with ECC (error correcting code) and write-switch protection. They’re resistant to extreme temperatures and the outer construction is also X-ray proof so your do not lose data when your device is scanned by a X-ray machine at an airport. Not sure if that is actually possible, but it is the only example why you would need X-ray proofing unless you are a spy.
The key feature for me is the UHS-I specs/technology. To keep things short and simple, it is the next step in memory card classes. The fastest class based SD card is a class 10 which is 10 MB/s. The UHS-I, using a clock rate roughly 8 times faster, reaches the 95 MB/s read and 45 MB/s write speeds on the new ADATA SDHC and SDXC cards. This new speed literally put these kinds of cards in a class all by themselves.
Why spend hundreds on a Android or Windows 7 based smartphone or tablet PC, only to cripple its performance with a “regular” SD card for your storage? The same goes for those with mid to high quality digital SLR cameras who shoot in burst mode or HDR. Get a card like these and let your portable devices show you what they really can do.