I think it is important that educational 'country clubs' make blogging recognition available, but not insinuate that blogging is mandatory.
This post is an amazing example of how my newsreader has pruned my search engine. I was only just this morning asking myself this question, making a mental note to look up some discussion on it, when low-n-behold, here it is in my newsreader fed by Will Richardson's blog!
Will points to Konrad Glogowski has a post up titled "Grading Conversations"
...What this means to me is that grading blogs (especially at the elementary level) has to be a very holistic process that focuses not only on the quality of their work but also on the extent to which their work reflects the context in which they work. I think that student bloggers should be recognized for writing as part of a larger community of inquirers.