The announcement may be a bit difficult to read (apparently a poor Japanese to English translation), so I'll explain:
Quote: * Compatible with SDXC memory card. (Transfer rate is not compatible with UHS speed class)
This delivers the promised SDXC support for the K-r and K-5. However, the camera cannot communicate with UHS cards (such as
this Kingston card) at UHS-1 speeds, probably due to hardware limitations.
Quote: * All ISO sensitivity setting can be used on Bulb mode.
The ISO 1600 limit on Bulb exposures is lifted, allowing all possible ISO sensitivity settings to be used in Bulb up to the camera's normal limit.
Quote: * Improved functional sequence for Contrast AF and improved total speed until in focus.
Contrast detection AF algorithms have been improved, reducing the amount of time needed for the camera to focus in Live View.
--DragonLord