Microsoft's Mike Ybarra has stated that the company is working to bring the ability to purchase Xbox 360 backwards compatibility titles on the Xbox One this week. It was previously announced as part of this month's preview builds, but has yet to make an appearance. It's important to note that Ybarra stresses that it may become available later this week. That is the goal that is set currently, but unforeseen circumstances could always change that. Ybarra's tweet said:

"Lot of questions on this: Goal is for the ability to purchase 360 BC games on Xbox One to be in Preview late this week. Key word: goal. :)

Now, we just wait. Hopefully Microsoft is able to get it out to everyone this week as they plan.

Source: Mike Ybarra (Twitter)