The Raspbmc distribution of XBMC for the Raspberry Pi has had its monthly updated. The May update includes XBMC 13.1 which has a lot of bug fixes in the build as well as a new kernel (3.12), improvements to the file system, improved wireless support, TVHeadend fixes amongst other fixes.
Just reboot your Raspberry Pi to get the update, here are the changes to Raspbmc via the Raspbmc blog:
Upgraded the kernel to Linux 3.12 (for new installations only)
Improvements to the F2FS filesystem
Improved wireless support
Add new firmware which resolves issues with 3D scaling and refresh rate switching
FIQ improvements result in better playback (less jitter) when using a USB sound card
Improve ease of enabling an external sound card in Raspbmc (Programs -> Raspbmc Settings -> System Configuration -> Enable External Soundcard)
Remove deprecated ‘Disable resolution limit’ option in Raspbmc Settings
Fixed issues with Wolfson DAC
Fix an issue where XBMC will repeatedly inform the user that an update is available, when it is not
Fix an issue where TVHeadend on new installations was not running; and upgraded TVHeadend to version 3.6
Fixed issues that Gotham caused with remotes
Updated the standalone image to include the Gotham release; as well as the NOOBS image.