This afternoon, I finally got past my status as a lone early adopter and was able to communicate with a friend or two via the new iMessage app -- and discovered a quirk that's necessary to communicate with the non-iOS 5 world.
Color my messaging
You probably know the basics of iMessage: you can send texts (and what most people paradoxically call "picture texts") directly from one iOS 5 device to another directly via the Internet (mediated by Apple's servers) rather than using the SMS or MMS infrastructure that your cell phone provider runs (and charges for). This might save you some money in texting fees, though if like me you're already used to paying for an unlimited texting plan, you'll probably need to get a lot of friends on iOS 5 before it becomes worthwhile to switch to something cheaper.
One facet of iMessage that's interesting is that, in bypassing the mobile carriers' messaging functionality, you're actually bypassing the need to have a mobile carrier altogether. Any iOS 5 device can send iMessages, and that includes iPod Touches and Wi-Fi only iPads. In fact, the first true iMessage I received was from a friend with an iPod Touch.
I did notice one quirk in how these messages were handled, though. That note was from my friend Matt, who had been texting me from his non-smartphone yesterday. Even though the iPhone was smart enough to recognize that the iMessage was from Matt (based, I'm assuming, on the email address he used with his Apple ID), it kept iMessages and SMS messages separate in its top-level list.
Will the real Matt please stand up?
This is at first confusing -- why can't I just have one central location for my Matt-messaging needs? -- but ultimately necessary if the thing is to work correctly. A message sent to Matt via iMessage won't get to his phone, and one sent via SMS won't get to his iPod Touch. You need to have two different methods of texting him, inelegant as it may be. Further inelegance arises if you tap the "Send Message" button from Matt's entry in the Contacts apps:
Many choices, numbers obfuscated for Matt's protection
Note that you can send a message to any of his phone numbers or to his email address. If you're a normal human who doesn't obsess over how iOS 5 messaging works, you might assume that tapping his email address would open the email client. In fact, it kicks you back to iMessage -- specifically to the screen where you can send him an iMessage. You can tell because the speech bubbles are blue. Tap a phone number, and you get the screen to send him a normal SMS, denoted by green speech bubbles.
Of course, all of this clunkiness is swept away if you're exchanging messages with an iPhone user, as Apple can be reasonably sure that either SMS messages or iMessages will arrive at the same destination. When another friend of mine texted me to boast that he had upgraded, the new messages appeared in his existing message stream -- but in a new color.
So, all we need to do to get iMessage to work this smoothly all the time is wait until everyone on the planet has an iOS 5 iPhone or (I assume) 3G iPad. (Note: This will never happen, sorry, you will just have to deal with having two entries in iMessage for your friends with iPod Touches.)