A search under "Louise Brooks" brought up eight results, including two cigarette card images of the actress and six images from her days with Denishawn. Oddly enough, the NYPL has especially strong holdings in these two areas - cigarette cards and Denishawn. Scans of some 21,206 cards are online now. While a search under "Denishawn" brought up 78 pages of results. I did a few other random searchs. "Clara Bow" brought up seven results. "Rudolph Valentino" two results. "Charlie Chaplin" three results. "Buster Keaton" four results. If you are looking for something, it seems best to search under different keywords. A search under "Ziegfeld Follies" brought no results. While "Ziegfeld" brought four results.
The database seemed slow to respond (and display), but I am sure it is being overrun with search queries. Also, I wasn't sure if more than thumbnail images were displayed for any given entry. I couldn't get larger scans of the Louise Brooks thumbnail images to show. Here is a link to the New York Times story on the debut of the collection. Happy hunting.