Late breaking story but we have confirmation that Windows Phone 8.1 has finalized today, at least for the Core team. That’s still not technically a 'Release to Manufacturers' (RTM) because the Consumer Experience (CXE) team still needs to work out a few bugs. That will happen over the next couple of weeks before it is shipped to OEMs to put on new devices.
Microsoft is expected to unveil Windows Phone 8.1 next week during Build, where we will bring you the latest coverage live. The Developer Preview release though has been delayed by about a week from the original plan. Still, developers in attendance are expected to get a surprise or two to take home.
From Windows Phone Central to the Windows Phone team, congratulations!