Starbucks plans to roll out this service across the country in 2015. The service only works on iPhones now, but Android support is planned as the service launches.
Unfortunately, there is no word on Windows Phone support. Actually, Starbucks still hasn't even launched a standard Starbucks app for the Windows Phone platform, despite the fact that Microsoft and Starbucks are both head-quartered in Washington State. There is a Microsoft Band Starbucks app so it continues to confuse me why there is no official Windows Phone app.
The new Mobile Order & Pay service lets you place a food and/or drink order, including all drink customizations that customers like to make, in the app. You then select a store to pick up your order with approximate wait times and directions to the store appearing on your phone.
Payment is made from your Starbucks card so along with an iPhone you will need to have a valid Starbucks card to use the service in Portland.