It’s a known fact that Windows Phone Mango supports WiFi sharing by default. But the same was not the case with Nokia Lumia 710 or 800. And now, this is going to happen soon. WiFi sharing is going to come as a default feature in the Lumia 7610 and 900 and would come as an update for Lumia 710 and 800.
There was an update out for Lumia series recently regarding improvement of the phone’s battery life. The reason why the WiFi sharing update wasn’t combined with the battery life update was so that users who do not wish to have the WiFi update are not compelled to have it, which otherwise would have been updated in their Lumia phone forcefully. Though, the WiFi sharing is more used to connect to data-hungry devices, such as laptops and tablets.
Date is not fixed, but it is confirmed that this update will be out by next week.