It's from Lombard's first RKO film, "In Name Only," and shows her and co-stars Cary Grant and Kay Francis. According to the seller, it's 11" x 14", in near-mint condition, and it's a design I haven't come across before, so it understandably is considered valuable.
That's what the seller is looking for, under eBay's "buy it now" option. I'm not a professional collector, so I honestly can't gauge whether this is the price the market will bear, but this doesn't appear to be an item for the casual buyer.
To learn more about it, go to http://cgi.ebay.com/IN-NAME-ONLY-39-CAROLE-LOMBARD-CARY-GRANT-LOBBY-CARD-TC_W0QQitemZ160372467272QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item2556f1a648.