Cingular-AT&T Wireless Merger Complete
While text messaging has been up and running for nearly a decade or so in Europe, they didn't pick it up for a long time in the U.S. because the industry as a whole didn't care for how it was implemented.
It's turned out to be something of a mixed blessing. Text messaging, which was originally created so that cell companies could update their phones over the air, all travels through third party carriers, which is why you can send a text to most anybody (at least intranationally, international tends to be a bit of a hassle in many cases, though T-Mobile seems to mostly have that beat), unlike MMS, which is mostly intracarrier protocol driven, and thus conflicts badly with other carriers.
The issue the U.S. has run into with text, besides the fact that it's relatively new (though believe me, the kids at school where cell phones are allowed love it) is that the companies have a lot of issues deciding how they're going to bill it.
You're generally more likely to find plans with unlimited internet than unlimited sms, because the general business model dictates that you're going to get your money off of per use 10 cent charges, or what have you.
But then, most of the US data models are a little strange.