Following the release of iOS 7.1.2, Apple also pushed OS X 10.9.4 to Software Update, bringing WiFi-related fixes and Safari 7.0.5 to Mavericks users. The new version includes a fix for a bug that prevented Macs from automaticallty reconnecting to known WiFi networks and improves the reliability of wake from sleep. An issue that caused "the background or Apple logo to appear incorrectly on startup" has been fixed, and an updated version of Safari (7.0.5) is bundled with the update as well.
OS X 10.9.4 is available now from Software Update through the Mac App Store. You can find the direct download links below.