Brandon suggests a definition he has worked on with Jim West:
A biblioblog is a weblog that focuses primarily on Biblical Literature, related fields, and occassionally [sic] contemporary events. It's [sic] purpose is to offer news, opinion, and conversation for those interested in the Biblical text. Biblioblogs occassionally refer to personal matter, but that is not the primary focus.I would say that one can state it much more simply. They are:
Blogs which have a primary focus on academic Biblical Studies.The "primary" implicitly makes clear that all the other stuff mentioned in the definition above (contemporary events personal matter, etc.) may be there to a lesser or greater degree in different blogs. I, for example, tend to avoid talking about contemporary events unless they are related in some way to academic New Testament studies, however much I might be tempted, while others speak at greater length about them. It's a question of style and personal preference and overall aim. I would also add that the word "academic" is especially important -- it makes clear that the subject matter is written by academics for academics and those who enjoy reading academic material. In other words, there is a focus on critical Biblical scholarship.