Would the increased use of Mobile Phones, like the iPhone, promote less blogging and when bloggers to post to their blogs - shorter blog posts?  According to Steve Rubel at Micro Persuasion, the answer is yes.

"..Second, there's the proliferation of mobile Internet usage. I don't have the statistics handy but my gut is that the upper strata of Forrester's participation ladder includes many smart-phone owners.

As a reporter from MSNBC found, you can increasingly do a lot with these devices by themselves. On my next short trip I plan to leave my laptop at home in favor of my iPhone, especially if I can plan it all so that I am around wifi.

What this all means is that mobile platforms and devices encourages people to publish more often, but in a far shorter format."

Many blog posts are too long - including some of mine.  I'd actually like to post more from my mobile phone - but it does not work for me.  Maybe it works on the iPhone, although I understand the browser does not yet fully support for JavaScript.

I think we continue to evolve but and maybe as blogs have now become mainstream, people are using more direct ways to communicate via Twitter, or whatever else is out there to use; people will continue to blog - but as mobile devices improve, they will use them more to post and communicate.

As a Web Analyst, I'd look for Mobile Device Usage going up for segments that are then blogging less - where you could make an association between the two.