Tom Coates had some people graph posting patterns through his 5 years of blogging. I guess the move from plenty of short posts to sparser, longer posts, is a trend shared by many long-established blogs. It's definitely been true for me over the last four years. Now that there are so many blogs and meta tools, there's less interest in just posting what everybody else is blogging about too, unless you have what you hope is a valuable, if not unique, perspective to add. I'm munching on topics for a while if they've already been mentioned in the parts of the blogosphere I belong to. A quick comment on someone else's blog, or a side link, are replacing those full-fledged posts that tend to say: "hey, read me, this is worth a feature on the main blog." That doesn't mean every post needs to be a long essay or article, but you end up striving to add some angle to everything you publish.