Voice is a feature that made its debut on its own grid and beta viewer in March of 2007.
It was recently (May 2007) rolled in to the main beta grid, and Linden Labs has put out June 13 as the day that the main viewer with voice will be completed. Whether this means that voice will be added to the main grid is unclear.
Voice will be available free for landowners during the beta. Owners of mainland and island properties will be able to use the new feature for free. However, owners of older islands who pay fees lower than the current $US295 per month may have to upgrade to be able to use voice.
While many believe that voice in SL will be beneficial, some users are against the addition of voice to the main grid.