Apple on Monday released OS X 10.8.4, the latest version of its desktop operating system that the company says will deliver improvements to enterprise Wi-Fi connectivity, compatibility improvements between Microsoft Exchange and Calendar, the ability to make FaceTime calls to phone numbers outside the United States, improved VoiceOver compatibility with text in PDF files and the newest version of its Safari browser. This marks the first major update to OS X Mountain Lion since Apple released OS X 10.8.3 in March.