We really do need a common denominator for TIME units within the blogosphere...i.e. a time based activity extensions to RSS. Why you ask?
Well, I can think of many applications to it but one would be; "Means times to respond" or MTTR (pronounced exactly like the word "meter") - this would be the average response rate calculated to the average minute (universally based upon the 24hr military clock)...from the time a blog is published, a comment is made, and the owner responds. In addition we will obviously need a per post MTTR.
I posit that we also need a "participant interaction" MTTR - i.e. excluding the administrator or owner of that blog. This would be a very good indicator of the community participation and activity rate(s) within blogs.
Various subsets of these MTTR's would be needed - summary MTTR for entire blog + summary MTR per post.
Commentators and blog respondents should also have an MTTR tag associated with their identity/handle/unique ID. We could tell whether a contributing commentator is really active or just a chancer ;)
These time measurement stats would then be clearly labeled on the home page of a blog - so you can tell whether it is very active, old or relevant. e.g. Wouldn't it be great to do a Google search on "Aquilla Microlight Aircraft blogs MTTR = 12 hours"...? This would result in "fresh" blogs retrieval vs just a dredge and mash of old and new content.
Now link that MTTR to a scoring variable...and the scoring was a public scoring that each blog admin assigned to the commentator...and people participating in the various threads could also score the commentator. We could pick up high quality and very active blogosphere citizens and perhaps harness them...pay them to participate and interact...
Ok - back to work ;)