It is not yet available, and it is rather difficult to get information about its contents, but an interesting new book is coming out next year on Orthodox theology: The Cambridge Companion to Christian Orthodox Theology. I do know that it will have a submission from Prof. Papanikolaou of Fordham, who recently organised a conference on Orthodox readings of Augustine (whose papers will be published in a volume edited by Papanikolaou and Prof. Demacopoulos) and who has also written a work on the Trinitarian theology of Lossky and Zizioulas, Being with God: Trinity, Apophaticism and Divine-Human Communion. I would have very much liked to attend the Augustine conference, but the timing was no good for me. Another excellent (and expensive) collection of papers that came out in recent years, unrelated to Prof. Papanikolaou, was the volume Byzantine Orthodoxies, edited by Prof. Louth, which has a wonderful paper on the Arian controversy by Fr. John Behr and another on the Synodikon.