The Messages App, available as a beta download, is pretty nifty: it automagically syncs your Mac texting to other iOS persons with your iPhone and/or iPad. This re-introduces a kind of instant messaging back to the computer, which is something I haven't done in a long time. Somewhere along the way, email and then texting killed instant messaging. I rarely use instant messaging unless the person is in another country, or I'm offering someone some technological help.
A larger question for me is, what about privacy? If you're like me, you use texting for the informal and direct communcation with friends. Email has long been the purview of official correspondence or conducting business. Work and business so invaded email that many people use it infrequently these days; it became something like checking the mail for bills and statements, rather than an actual communication with a friend.
Texting is more personal and is, therefore, something I don't want to just show up on my screen on my laptop. What if something is read by the wrong person, or misunderstood? What if a joke between friends is read by someone who doesn't know it's a joke? Texting becomes different if it's popping up in various places, instead of going from one phone to another, which is how we tend to imagine texting: it's quick, easy, direct, and secure.
One could quit the Messages application, but that sort of kills its usefulness, as it's supposed to be right there and in sync, if it's to be really useful. There's a weird trade-off here, as the directness and invisibility of texting is now something more ubiquitous and visible.
The Messages application and iCloud sync changes the tone of texting – the text goes from your iOS device to Apple's servers and then your computer screen. Be aware of this, if you use Messages, and don't leave the application just running in the foreground for all to see.