Found this on Dutch site (http://nl.forums.wordpress.org/topic/woocommerce). Not sure it is same problem.
Open functions.php and fine this line: (line 40)
add_theme_support( ‘post-thumbnails’, array( ‘post’ ) );
Change that into:
add_theme_support( ‘post-thumbnails’, array( ‘post’, ‘product’ ) );
Save.
This should be the result:
http://f.cl.ly/items/081s3r0R110q3Y1D2T08/screen-capture-1.png
Since I also wish to add WooCommerce to Pinboard site (www.homestylers.nl) I would like to know whether above or sth else solved your issue. I have not tried it myself yet.
Nicolaas