The Globe and Mail's Ivor Tossell laments that the cool people aren't bellying up to the Twitter bar any more.
Maybe the problem is less with Twitter and more with the cool people.
From the April 10 Globe and Mail:
Things fall apart. Take Twitter. It's over, done with. It's an ex-songbird.
I mean, millions of people still use it, and more are signing up. People are rushing to the service, especially if they have something they'd like to sell you. But the people who drew me to it just aren't posting much any more. The new joiners, who mostly seem to be self-promoters of some variety, aren't the people I want to be talking to. The fertile conversation that made it such an amazing place seems to have faded. The spark is gone. It might be time to pack up and move on.
I used to enjoy this kind of thing. The Internet is a tribal place in which different demographics colonize different Web
services . From time to time, whole networks of friends migrated from one website to the next; it was fun trying to guess where the next socialnetworking stampede would occur. But here we had all just arrived on Twitter, and now people are dropping out again. My silly net generation has become digitally nomadic, wandering from one patch of the Web to the next. And I'm tired of it.Twitter provided a roost for tech and media types. And, for a while, it was making inroads into the general population. But now, it seems to be choking on its own success. Not only is it breaking down all the time, but the crowd has changed. It's getting flooded with celebrities and corporations, marketers and sundry PR offices, all pinging out press releases.
This makes it difficult for new users to see just what makes Twitter worthwhile. And while veteran users are keeping up the pace, the people I know who live outside the technology and media bubbles are using it less and less.
Tossell noted that when he started university in 1997, ICQ was the big thing. Then it was MSN, then Facebook and now Twitter. However, there is a social cost attached with uprooting, he said:
When you lose a social network, you lose friends. As long as the Web is made up of social networks that act like competing fiefdoms, trying to monopolize the social graph by grabbing the most users, it will always be this way.
I'll address Tossell's last point, but first, a point on that restless hipster audience.
I believe this Brett Lamb cartoon illustrates the problem nicely (if you don't know Toronto, Ossington is a rapidly gentrifying street between Queen and Dundas. Many bars have opened, and many tourists have poured into the area):

Lamb posted it on his blog, part of a series of 101 cartoons. You can see the original cartoon here (scroll down to no. 78).
As with so many things, the early adopters like things the way they were, and resent the new people who move in on the good thing they discovered. Speaking of being discovered, see this post on Tofino for another example.
But packing up and leaving Tofino is tougher than shutting down your Twitter account (although it's easier if you've been priced out of that bucolic little West Vancouver Island village).
Twitter might be less interesting for the Tossells of this world (and people even cooler than him, I might add). But there are w-a-a-a-y more regular people -- not to mention hucksters -- than hipsters, and that simple fact will influence the ultimate direction of Twitter and other social networks.
Tossell laments the cyber-friendships you lose when people move on to the next coolest thing, and others have written about the "walled garden" nature of social networks that compounds the effect.
I'll leave you with one last Lamb cartoon (did I mention he's a freelance illustrator?):

