Apple has made a few new changes to its first-party voice and text services in the newest versions of its mobile and desktop operating systems. Some users are reporting that iOS 8 now features the ability to create conference FaceTime Audio calls. Previously FaceTime audio calls could only be made from one user to another, but now you can add additional users to a call in progress.
OS X Yosemite sports a new addition to its iMessage capabilities. While screen sharing has always been possible over alternative services like AIM, Apple now allows you to use the built-in screen sharing feature in the Messages app over an iMessage account. Unfortunately the feature seems to be broken in the first Yosemite beta, but it is expected to be functional by the time the software ships.