Remember those crazy days of e-mail when you couldn't send messages between systems? Microsoft Mail customers could only send mail within their enterprise or to other customers of Microsoft Mail (ditto for the other systems). It wasn't until SMTP standardized things that e-mail could move between systems.
E-mail was interesting then, but it didn't really become dominant until it standardized around the SMTP messaging protocol.
Are we experiencing the same thing with Twitter?
Yes, it's a big (and growing) silo, but then, so were AOL and Compuserve in their day.
There is a better way, and it's arguably the direction the industry is going to need to take for microblogging services like Twitter to become as big as e-mail. We need to standardize. We need an SMTP-like standard for microblogging.
And, frankly, we need an open-source implementation.
Open-source Sendmail was arguably the first messaging system to embrace SMTP. Sendmail gave would-be e-mail adopters a free (as in cost and freedom) e-mail system to explore, which led to Sendmail becoming the world's most popular message transfer agent.
Microblogging could use the same, and StatusNet's open-source micro-blogging software could well play that role. StatusNet is the company behind Identi.ca, the microblogging platform favored by the free and open-source crowd.
In terms of public blogging, Identi.ca is still more a curiosity than a real contender with Twitter. But, as in e-mail, it's probably not wise to underestimate the value of an open-source approach to standardizing microblogging intercommunications, particularly as microblogging enters the enterprise.
For example, enterprises that want to move beyond Twitter's one-size-fits-all approach to microblogging might prefer Yammer's microblogging-behind-the-firewall approach, an approach that StatusNet also offers. But StatusNet takes it further by enabling enterprises to set up a micro-blogging service that customers, employees, and partners could collaborate on. A private-public microblogging network, as it were, and completely based on open source and standards.
AOL once sat atop the consumer e-mail world, even as Twitter dominates microblogging today. Eventually, standards won out in e-mail. I expect we'll see much the same thing in microblogging. The question is, how long will it take?