Thumbnails were not properly cropped before today, they were just stretched to a square shape on the gallery display page as you can see here: http://putpic.com/gallery/3922/2925370.
Now all image thumbnails are cropped so that the gallery page will display more neatly without skewing the images. This change only applies to newly uploaded galleries, as you can see here: http://www.putpic.com/gallery/3942/2306796.
This new thumbnailing method applies to all the upload methods (simple upload, java upload, zip upload). If you experience any troubles or find any bugs please do send your feedback to email@example.com.