The Samsung NX100 firmware v01.01 is described in detail (including installation instructions) in a PDF document available from the firmware tab of the camera's Download Center page on the Samsung US website. The new firmware is said to improve autofocus performance in the camera's night mode. Overall stability is also said to have been improved, but with no specifics given.
The firmware update itself is also available on Samsung's US website. European customers will find the same updates available on the UK-based Samsung Imaging website.