When I look at the start screen of my Windows 8 installation I see that bundled apps have colors from some standard(?) palette: IE and Weather have the same color, Store and Xbox Live Games, People and Music, Messaging and Maps, etc. It doesn't look like there's any logical connection between most of these apps. Yet their tiles share colors most likely coming from some standardized palette.
But when we create a Metro app in Visual Studio the Background color is preset to #464646 in a free form text field. So I wonder if there's some "official" list of the predefined colors we can use to make our own tiles "native" to Windows 8?
Obviously I can take a screenshot and pick a color from a bundled tile, but there has to be a better way and I've failed to find it so far.
Edit: apparently you can't even pick the color from a screenshot since a gradient is automatically applied to it by the OS:
If you make the space around the logo itself transparent in your image, your app's brand color (declared in the manifest) will show through with a gradient preapplied to it as part of the Windows 8 Release Preview look. http://msdn.microsoft.com/en-us/library/windows/apps/hh465403.aspx#using_default_tiles
Check my Metro Design Guideline presentation at https://skydrive.live.com/view.aspx?resid=40CFFDE85F1AB56A!1284 slide 55
The colors are:
PURPLE
RGB 162 0 255
A200FF
MAGENTA
RGB 255 0 151
FF0097
TEAL
RGB 0 171 169
00ABA9
LIME
RGB 140 191 38
8CBF26
BROWN
RGB 160 80 0
A05000
PINK
RGB 230 113 184
E671B8
ORANGE
RGB 240 150 9
F09609
BLUE
RGB 27 161 226
1BA1E2
RED
RGB 229 20 0
E51400
GREEN
RGB 51 153 51
339933