> When Twitter was gathering steam back in 2009-10, it did so because tweeting was done via SMS and not over a proprietary interface. I don't believe this for a second. In 2009-2010, there were already a huge number of smartphones and Twitter clients out there. In fact, that time was probably better for third-party Twitter clients than today. Smartphone growth exploded in 2009-2010, so the idea that "everyone was get…
Don't forget about Twitter's API and liberal usage policy that made the plethora of clients and mashups possible -- I think this accelerated their growth more than anything. Their API is not so "free" now -- you need to register your app, always authenticate, and there's no public firehose access any more.
Twitterrific was a jailbreak app before Apple even launched the App Store. Did Twitter even have an official iOS app before they bought Tweetie? That seemed like it happened around the time of the first big API lockdown.