Microsoft will host its annual E3 press conference very soon but it appears that their plans have been leaked. A new white "Xbox One S" is supposedly 40% thinner and has 2TB hard drive. It will also support 4K and HDR.
Xbox One S with 4K and HDR
The information has been leaked on the Neogaf forum and appears to come from Microsoft's official Xbox.com website. There are no details regarding launch date and price but a "pre-order" button suggests that the new console will not be released immediately.

In the two pictures a thinner Xbox, which will be named Xbox One S, is shown. The new console is white and reportedly 40% thinner. One of the persons who leaked a photo adds that the power supply will be integrated, too. As seen from the picture below Xbox One S will also feature a vertical stand.
In addition it appears that the Xbox One S will have a 2TB hard drive and support for 4K and HDR (high dynamic range). It is not clear how to interpret these details before Microsoft chimes in but 4K/HDR probably applies only to video, not games.

Microsoft will host their E3 press conference on Monday 9:00AM PT so we should have confirmation. You can live stream the event here.
- Source: Neogaf via The Verge