You are able to enable featured images for posts and hang their size using the following code inside your function.php file:

add_theme_support('post-thumbnails');
set_post_thumbnail_size(107, 69, true);

but this sets the look size globally for just about any publish types. Im using wordpress 3. and also have produced my very own custom publish type. Can you really use a different featured thumbnail dimensions for various publish types?

Thanks

Scott

Inside your theme functions file, you are able to define new image dimensions that affect any images submitted from then forward:

[cde]

Once you have defined a brand new image size, you should use the_post_thumbnail as always but range from the new image size to show that rather than the thumbnail default:

add_image_size('new-thumbnail-size',600,340, true)

A bit more detail: http://gavinsmith.me/2010/10/multiple-post-thumbnail-featured-image-sizes-in-wordpress/