Where is the place where actual size of desktop icons is stored?

As one can resize the icons on desktop (not within nautilus) through righ-click menu: "Resize icon..", so where is the size stored for that certain file.

File attributes for icons are stored in binary files inside ~/.local/share/gvfs-metadata/.

To read an attribute for a file you need to use the gvfs-info command supplied by the gcfs-bin package.

To read the complete metadata stored from a file/folder on the gvfs use gvfs-info -a "metadata::*" <path_to_file/folder>, ie

gvfs-info -a "metadata::*" /home/bruno/Desktop/Screenshot\ at\ 2011-12-14\ 21:29:29.png

attributes:
  metadata::icon-scale: 2.6875
  metadata::nautilus-icon-position-timestamp: 1323894580
  metadata::screen: 
  metadata::nautilus-icon-position: 77,15

To set an attribute inside the gvfs you use the command gvfs-set-attribute which is also part of gvfs-bin as this gvfs-set-attribute <path_to_some_file/folder> metadata::some-key "some_value"

If you want to change the scale of an icon in gnome you need to change the icon-scale attribute so for the file shown before if I wanted to reset the scale to 1 would do that as this

gvfs-set-attribute /home/bruno/Desktop/Screenshot\ at\ 2011-12-14\ 21:29:29.png metadata::icon-scale "1"

Unfortunately I could only see the changes after I logged off and back in on, unity --replace & did not do the trick. I am not sure if you can force Gnome to reload the data from the gvfs binaries.