About half a month ago, Microsoft began testing game gifting with Xbox Insiders. Today Microsoft's Brad Rossetti has revealed that game gifting is now available for all Xbox Insiders.
Xbox One Insiders - Preview Omega users we have just enabled Game Gifting for you all!
— Brad Rossetti (@WorkWombatman) November 8, 2017
More specifically, the game gifting feature has been opened up to the Preview Omega ring, the lowest and least risky ring of the Xbox Insider Program. This is also the ring that any average Xbox user can join, allowing them to test minor changes made to previously released monthly updates.
Given the timing, it also can be assumed that Microsoft may be pushing out the final update including game gifting to all Xbox users soon. The Omega group has been known to get early access to an upcoming update shortly before it goes to General Availability.
Game gifting works just as one can expect. All you need to do is to find the listing in the store, press on "buy as a gift," and then enter in an email address or choose from a list of friends. The recipient should then receive a message from Xbox Live with a redemption code for the game.