An article recently published in The Art Bulletin:

• S. Guérin, 'Meaningful Spectacles: Gothic Ivories Staging the Divine', in The Art Bulletin 95 (March 2013), pp. 53-77.

Volumes I and II of R. Koechlin, Les Ivoires gothiques français (Paris, 1924) are now fully available online, as part of Gallica, the virtual library of the Bibliothèque nationale de France:

• Volume I
• Volume II

On a statuette of the Virgin at the Metropolitan Museum of Art:

• S. M. Guérin, 'An Ivory Virgin at the Metropolitan Museum, New York, in a Gothic Sculptor's Oeuvre', in The Burlington Magazine, no. 1311, vol. CLIV (June 2012), pp. 394-402.

On the Gort casket, now in Winnipeg:

• P. Mae Carns, 'A curious collection in ivory: the Lord Gort Casket', in Collections in Context: the Organization of Knowledge and Community in Europe, ed. by K. Fresco and A. D. Hedeman (Columbus (Ohio), 2012), pp. 246-174.

Two articles in West 86th, vol. 18, no. 2 (Fall-Winter 2011):

• A. Cutler, 'Carving, Recarving, and Forgery: Working Ivory in the Tenth and Twentieth Centuries', pp. 182-195. Accessible online here.
• S. M. Guérin, 'Duplicitous Forms', pp. 196-207.

Studies in Iconography 32 (2011) contained no less than two articles on Gothic ivories:

• N. Rowe, 'Pocket Crucifixions: Jesus, Jews, and Ownership in Fourteenth-Century Ivories', pp. 81-120.
• P. M. Carns, 'Floire et Blancheflor: Gothic Secular Ivories and the Arts of Memory', pp. 121-154.

D. Gaborit-Chopin, 'Gothic Ivories: Realities and Prospects', in Gothic: Art and Thought in the Later Medieval Period. Essays in Honour of Willibald Sauerlander, ed. by C. Hourihane (Princeton, 2011), pp. 157-175.
More details here.

Trésors de la collection Daniel Duclaux (Angers, 2011).
This little known collection, housed at the Musée-château de Villevêque near Angers, contains, among other treasures, a few ivories...

P. Williamson, Medieval Ivory Carvings. Early Christian to Romanesque (London, 2010).
Paul Williamson published last year this impressive catalogue of ivories in the collection of the Victoria and Albert Museum, covering the Early Christian period to the Romanesque period. The objects are documented in an unprecedented way through detailed entries and numerous photographs.
The next volume, focusing on the Gothic period, is in preparation.

P. Malgouyres, Ivoires de la Renaissance et des Temps Modernes. La Collection du Musée du Louvre (Paris, 2010).
A publication covering ivories from the 15th to the 19th century in the Louvre and complementing the catalogue written in 2003 by Danielle Gaborit-Chopin.