My friends have arrived in Lisbon, well some of them anyway, and where a few years ago BlackBerry BBM was the way we all would have been staying in touch what seems to be the common denominator isn't even the globally popular WhatsApp, the OTT SMS service, but instead its Apple's iMessage.
And, its not because of iPhone but because of iOS. Yu see, everyone isn't using their iPhons due to roaming charges or the fact that they may have a locked phone. But on Wi-Fi, using accounts from FON, Boingo or others, they can still be connected to one another and keep in touch.
We also can go one step beyond, with "Find Friends" which is an iOS app from Apple that is a lot like Google Latitude.
Between the two services, iMessage and Find Friends, neither requires carrier involvement, if you don't wish to go local. In my case, with unlocked iPhones and my iPads and SIMs from Vodafone, I'm pretty much staying in touch with everyone.
Does this mean I've abandoned my BlackBerry--NOPE. I still have it, use it and find a lot of benefit with it. And when BB10 arrives with new devices, and new apps I wouldn't be at all surprised if my usage levels increases as there are just somethings a BB is simply better at.