Just to give a idea about how I use multiple colors:

*yellow for simple highlighing
*orange (which I would like rather than pink) for key information
*green for definitions
*blue for any procedures or instructions

This means that I use all four colors for private or public notes. Perhaps the text public or an always visible icon appended to public bookmarks would make for sense rather than a highlighting color.

Personally, I would like to have at least two highlighting colors (orange and yellow) to be able to differentiate between important and less important color. If this feature is implemented, I would also like the option to organize web-clippings by colors (ex. all orange highlights followed by all yellow highlights) and also to see all highlights in order.

I understand that, but I would still like the option to have two highlighing colors for my private notes.