Thank you for taking the time to report this bug and helping to make Ubuntu better. I have just confirmed this bug with Firefox 3.7 on Ubuntu Karmic, so I am marking it as such. The lack of an icon for images may be due to the fact that the icon for an image, in a folder or on the desktop, is a small preview of the image. However, there is a generic icon for .zip files that does not seem to be used. I will continue to test this issue and will report back any findings.
Thank you for taking the time to report this bug and helping to make Ubuntu better. I have just confirmed this bug with Firefox 3.7 on Ubuntu Karmic, so I am marking it as such. The lack of an icon for images may be due to the fact that the icon for an image, in a folder or on the desktop, is a small preview of the image. However, there is a generic icon for .zip files that does not seem to be used. I will continue to test this issue and will report back any findings.