Through the Gretchen McCulloch blog I didn’t know existed I am introduced to Tanadrin’s “one hundred percent true and correct etymology” of blagosphera.

Blogosphera is naturally 1st declension (the medieval form form of blogosphaera, from the Greek βλωγοσφαῖρα), blagosphera is actually the neuter plural of the rarely-attested blagospherum, itself derived from the earlier blagospes, “to check a blog in the hopes it has updated in the last five minutes, even though it almost certainly has not.”