Apple has released the 10.9.2 update, recommended for Mac users running OS X Mavericks. It includes improvements to the stability, compatibility and security of your Mac.
More information and installation help can be found here: http://support.apple.com/kb/HT6114
This release follows another critical update for iOS 7.0.6, which is now the current version for iPhone, iPod touch and iPad. Users of Apple mobile devices should upgrade to this version, if they have not already.