Actually, I traced back who made the icon and asked him to provide the source (SVG) files. They are attached to this bug report [1] now, and await being added to PiTiVi.

Andreas shared with me his concern for making a high-resolution, high-detail SVG version for a 256x256 canvas (like this: [2]), but still hasn't gotten around to it for lack of time.

[1]: http://bugzilla.gnome.org/show_bug.cgi?id=573997
[2]: http://dl.getdropbox.com/u/107961/whooooah.png