It's happening. Twitter changed.

Remember when I said this yesterday?

"What would happen if, say, tomorrow Twitter decided that all Twitter clients (third-party and official) had to show some fairly obtrusive ads or you’d need to pay a few dollars per month to use the service?"

It turns out Twitter did change the next day. (I knew nothing of #letsfly at the time, I promise.)Marco Arment, today, whilst linking to John Gruber's thoughts on the matter.

"I’d wager that all third-party clients will be forced to display the trends and ads within a year, and what we know as Twitter today — or at least what we knew until yesterday morning — will be a distant, quaint memory: Remember when it was _just_people you followed?"

So, it is happening. Twitter has changed. In the blink of an eye its most loyal users are second-guessing its future. It pulled a Facebook. And I'm guessing that Marco isn't too far off in his estimate. Twitter will never be the 140-character simple messaging system that we all fell in love with in 2006.