Seems good! Instead of having the "add color to group" entry in the color edit popup, how about sticking to drag and drop? Or having something like cutting and pasting colors? This would be closer to cutting/pasting layers.
Also, will it be possible to select a range of colors? With a main selected color and a selection, a bit as with the layers and frames in the timeline, this would make the whole system intuitive and revolve a bit more around gestures/dragndrop.
If you have groups, palettes, the ability to search by name, what will the tags be for? Have you thought of some predefined tags to get a sense for their use? Palette dockers are so much simpler in other programs I can't imagine what to use them for. Is it just like the paintoppresets?

I don't know exactly what's planned for the first release of this new palette, usability-wise / like what's the time budget. But seems nice so far!

Tags aren't necessary in the palette itself no, but they are in the palette chooser... I've had a lot of trouble communicating the difference between the palette docker and the palette dropdown to scott, so that might be my fault as well.

Multi-drag and drop will rely on @rempt Qt does have a sort of system for drag and drop, but it isn't setup to handle our kocolor object yet, so it kind of depends on how much rempt wishes to do, though we did seem to agree that drag and drop organisation was the sanest to use.

Oh right, you'll have tags assigned to the palettes themselves, is that so? I understand now.

This is how I currently think it works...

Tags are directly associated with palettes. You can assign a tag to a palette. By selecting a tag, it will filter the palettes listed.

There are no tags for colors or color groups. Color groups manage a list of colors. A color palette may, or may not, have a list of color groups that are associated with it.

In terms of hierarchy :

Color Palette

• Color Group
  • Color

Let me know what I am missing

Wow! This palette looks really powerfull, although for unskillful users like me, this palette could go unnoticed.
Now that I think about it... I usually saw many speedpaints and the truth is even many artist doesn't use the panel of color palette.

Any way, this update could worthwhile.

Btw, an option to create a new color palette from a selection also could be awesome.

It never occured to me that we could use the tagging system to group palettes and be able to display the groups we choose, neatly separated from one another. Great idea, I like the mockup a lot!
I am not sure if it is the right place to discuss this, but one thing I am missing is some arrangement options for the colors in a group: Arrange the selection by Value, Saturation or hue for example.