But frankly, I think that neologism rather silly. What does it mean, exactly? Blog-O-sphere? What?
Thing is, the “o” in other spherical words (biosphere, bibliosphere, geosphere, and so on) is part and parcel of the prefix. It’s not separate and apart. And so I haven’t inserted it here.
Course, if I wanted to be true to the roots of the thing, sphere wouldn’t come into it at all. Web is Germanic word (from Old English), and log‘s from Old Norse, and so “blog” has its roots in Teutonia. I suppose the most accurate thing would be to call this a blogworld, world being Germanic as well. Sphere and globe are far more Mediterranean in origin.
Just my humble opinion.