Well to quote Wiki "Biblical theology for the most part is a Christian approach in which the theologian studies the Bible from the perspective of understanding the progressive history of God revealing Himself to humanity following the Fall and throughout the Old Testament and New Testament. It particularly focuses on the epochs of the Old Testament in order to understand how each part of it ultimately points forward to fulfillment in the life mission of Jesus Christ. Because scholars have tended to use the term in different ways, biblical theology has been notoriously difficult to define. When Biblical theology seeks to understand a certain passage in the Bible in light of all of the biblical history leading up to it and later biblical references to that passage it is systematic, historical and dogmatic theology."
To me this seems to be the approach of most study Bibles... Indeed the only study Bible I have ever seen that I would consider Systematic would be the "Disciples Study Bible" (this is a wonderful resource and would love to have it in Accordance... it is currently only available in WordSearch, a Bible software program that lacks much). To me "Biblical Theology" almost sounds like an almost meaningless catch phrase. That cynicism put aside it offers a laudable goal, and allows us at best to view christ as through out the Bible start to finish. This is accomplished in Gospel Transformation Bible without doubt, but this not so in the ZSB, looking at Esther The introduction accomplishes the goal of 'Biblical Theology' but Jesus Christ makes no appearance in the notes till Esther 5:2 and only there in the entire book's notes.. Now the notes are all good but all in all far different from GTB notes. That said looking at a commentary with a goal of Biblical theology in all but name, [The People’s Bible is just what the name implies—a Bible for the people. It includes the complete text of the Holy Scriptures in the popular New International Version. The commentary following the Scripture sections contains personal applications as well as historical background and explanations of the text. The authors of The People’s Bible are men of scholarship and practical insight, gained from years of experience in the teaching and preaching ministries. They have tried to avoid the technical jargon that limits so many commentary series to professional Bible scholars. The most important feature of these books is that they are Christ-centered. Speaking of the Old Testament Scriptures, Jesus himself declared, “These are the Scriptures that testify about me” (John 5:39). Each volume of The People’s Bible directs our attention to Jesus Christ. He is the center of the entire Bible. He is our only Savior. The commentaries also have maps, illustrations, and archaeological information when appropriate. All the books include running heads to direct the reader to the passage he is looking for. John F. Brug, Ezra, Nehemiah, Esther, The People’s Bible (Milwaukee, WI: Northwestern Pub. House, 1985),] and even in this Christocentric series Jesus is not often referenced in the commentary on Esther. I feel like I am somewhat failing to answer your question, but maybe someone else can come along to offer you a better answer.