As has been said this is the new default icon for the explorer in Windows 7
However, it is not fixed and can be easily changed
Right click on the taskbar icon to show the jumplist.
right click on the Windows Explorer entry on the jumplist.
Select the Change Icon option from the presented dialog.
Browse to an .Ico or suitable .dll file and select an icon.
Ok out of the dialog to set the icon
It may take a reboot or log off to get the change to take but I assure you It does work
None of these icons are original other than the bin and start button