It wasn’t that long ago that having a Facebook account was unusual for someone not in university. I can still remember telling people that I had one, and getting nothing but blank stares — and now most of those people have an account, or have at least heard of it. I’m also old enough to remember when a chat application called ICQ came along in 1997, and I quickly became a heavy user, along with some of my close friends. No one else had any idea what we were talking about then either. But by 2000, Microsoft had launched Messenger, and within a couple of years it had hundreds of millions of accounts.
Is the potential market for a “group chat” application like Twitter as broad as the market for instant messaging apps? Probably not — especially with a 140-character limit, which some people might enjoy as a kind of haiku-style restriction, but some would likely see as ridiculous (is there a shortage of electrons?). And it may not be as large as the market for Facebook either. But I don’t think the concept of Twitter is quite as foreign as many people make it out to be — and certainly no more foreign than the idea of “instant messaging” was not all that long ago. And as MG Siegler notes, there are some pretty cool apps being built on top of it.
Mike Arrington has some Twitter stats from a source inside the company.