According to The Verge, the update will bring support for 1080p displays for 5-inch devices, and possibly even some bigger gear. Android flagships are already at 1080p, although we’re still not convinced that 1080p makes much sense on sub 5-inch devices.
In addition to high res screens, the update will also feature support for new Qualcomm chips. This means we should see Windows Phone 8 devices based on Snapdragon 600 and Snapdragon 800 SoCs by the end of the year.
It is still unclear when the update will land, we can only guess that it will be ready in time for the holiday season.