The information comes from sources familiar with Microsoft's plans, and thus is not official. According to the sources, the button will not include the traditional Start Menu, but instead will just be a way to access the Start Screen. The button is said to look nearly identical to the existing Windows flag that is used in the Windows 8 Charm bar.
The earlier rumblings about the restoration of the Start button included information that Windows Blue would include a boot to desktop option. The new report indicated that the second option is still in the works, as well.
Microsoft explained the Start button removal by saying it used data it had gathered from its Customer Experience Improvement Program. However, Start Menu replacements such as Pokki, Classic Shell, and Stardock -- and their popularity -- are evidence that Microsoft may have made a mistake.
In fact, though Microsoft said that removal of the Start button is due to customer feedback, so is its restoration.
As usual, Microsoft will release a Windows 8.1 Public Preview before the product goes final. We'd hope both of the options above are in the Preview, as Microsoft should try to get as much feedback as it can before the final version, due later this year.