Comment 13 for bug 553256

This was fixed on my fresh install of Natty (using Unity) along with bug 740540. I checked on a new user account.

There is a system-file-manager-panel.svg icon for both ubuntu-mono-dark and -light.

Jorge: Are you using Gnome Classic? Did you resize the gnome panel containing the indicators? If so, that's a different bug. There are currently only icons for sizes 13, 22, and 24. It should be fixable if a scalable version is specified. If you're using Unity or haven't resized your panel, can you attach the output of this command:
  find /usr/share/icons -name system-file-manager-panel.svg