Apple today seeded build 13C48 of OS X 10.9.2 to developers, marking the fourth beta iteration of 10.9.2. The release comes a week after the third OS X 10.9.2 beta, build 13C44, and a little over a month after the first OS X 10.9.2 beta.
Apple continues to ask developers to focus on mail, messages, graphics drivers, VoiceOver, VPN, and SMB2. Earlier betas of OS X 10.9.2 began allowing Mac users to block people on iMessage and FaceTime, as can be done in iOS 7, and also introduced FaceTime Audio.
Article Link: Apple Seeds OS X Mavericks 10.9.2 Build 13C48 to Developers