1. Blog postings that subtly and passive aggressively take a shot at someone else, based on their blog postings. Blog. Repeat.
2. A war of words. No actual combat will ever take place, aka no actual verbal confrontation in the physical world will ever happen.
Lucy blogs about something she reads on a frenemy's blog. The frenemy reads her blog posting and retaliates by posting her own blog entry that subtly and indirectly takes a cheap shot at Lucy's blog. The blog wars start. This continues until one of them finds it boring and stops, though this may never happen.