Apple has released Mac OS X 10.9.1. You can obtain it via the Mac App Store. According to Apple, the update:
° Improves support for Gmail in OS X Mail, and fixes for users with custom Gmail settings;
° Improves the reliability of Smart Mailboxes and search in Mail;
° Fixes an issue that prevented the contact groups from working properly in Mail;
° Resolves an issue that prevented VoiceOver from speaking sentences that contain emoji;
° Updates shared links periodically when open in the Safari Sidebar.