Partial list of features for Windows Phone 8.1 GDR1 update include apps for a smart case
Another new change will be to the Windows Phone Store tile, which will become a Live Tile when set at medium size. Speaking of the tiles, GDR1 will allow manufacturers to set up the layout of the home screen tiles. Additionally, for those models that come with a microSD slot, manufacturers will have the choice of allowing the slot to be used for phone updates. The "auto scan for updates" setting can also be hidden at the discretion of the manufacturer.
A default setting that automatically shows the number dialed when calling voice mail, can be disabled in GDR1, and manufacturers can specify the series of numbers that the phone reads as being a phone number. Lastly, video shot by the phone's user in MP4, will contain metadata revealing the date the video was shot, and the location.
The GDR1 update is expected to be found in newly launched Windows Phone models starting in the August to September time period, and covers new Lumia models released during that time span.
source: NPU via WMPoweruser