sure why Sony seems to feel the need to come up with a new naming scheme every time the company has a new, slightly faster Memory Stick product and the latest model just has a ridiculously long name, as it's called the Memory Stick PRO-HG Duo HX.
This latest Memory Stick offers 20MB/s read speeds and 15MB/s write speeds, which is somewhat behind the fastest SD cards out there which are hitting 30MB/s for read and write. The PRO-HG Duo HX will be available in capacities of 4 and 8GB and comes bundled with a USB card reader.
No pricing was revealed in the press relase, but Sony will start shipping the PRO-HG Duo HX sometime in October.
You can find the press release here