Hi there! i found why SexyBookmarks doesn't send the post image when I share articles on Facebook?
The answer is Featured image function on WP 2.9+ and after.
If in your post set featured image then the SexyBookmarks doesn't sent the post image on Facebook.
If you don't set Featured image, SexyBookmarks sent the image on facebook!
Can you check that??? i think it's it to easy to you to set to take the first image of post on the SexyBookmarks code.