Sandisk has announced the world's first microSDXC card which has been designed to use on smartphones. This essentially doubles the maximum storage of modern smartphones and tablets. But since none of the current generation devices are still compatible we will have to wait a little longer.
The memory card is a class 6 device with transfer speeds upto 30 MB/S. The other factor is the price which is currently at a high $219. If you are looking to get your hands on one you can do so from SanDisk's online store.
source - SanDisk