We don't have a "press kit" for marketing materials. You can get common images such as logos at various resolutions / sizes from images.google.com.
Hope that helps. Perhaps
@cass or
@svk will reply with pgotoshop files if they have any to offer. I don't know which tools they use to produce their graphics, or if they are willing to provide native files for GIMP, Photoshop, Inkscape etc.
Good luck in your search.