Second Life, which had already announced its plans to add a voice option to the virtual world game, has made the voice option available on the Beta grid.
What is being called the Voice First Look Viewer is available for download to use in the live grid, meaning all users can now have voice options in their Second Life game. Second Life plans to run Voice on the live grid for a couple of months, and see how t goes, based on user feedback, but the company is looking to make this a standard feature on Second Life in the near future. You can check out all the known problems for Voice here. In order to use Voice in your Second Life game, you'll of course need a microphone, and according to Second Life, preferably digital US headphones.
There are a few known issues with Voice, some concerning one-to-one calls, which may fail on a random basis. There are some issues with invitations for one-to-one calls, and group chat as well (they may simply fail as well). There are a few temporary solutions recommended by Second Life for these known issues. Otherwise, hopefully these will all be worked out with continued use and feedback from users once the feature has gone live within the virtual world.