It’s good to talk, but how?

I say ‘talk’ but I was actually thinking about sending messages electronically rather than getting the vocal chords vibrating; the title just didn’t seem to work with ‘message’. So, to get to the point, I want to send someone a message from my iPhone, how should I do it?
Well, I could send a text and as long as the intended recipient has a mobile phone we are in business. The down side is it will cost me money and, from experience, they may not get the message until tomorrow or they may not get it at all.
How about Facebook Messenger? I can send a message, and even a photo, plus we can all get together and have a group bonding messaging session. Ah, my friend doesn’t use Facebook, back to the text.
Hold on though, after wasting a couple of hours of my life I installed IOS 5 on my phone yesterday; part of the reason I had no time to blog. This shiny new version of my phone’s software includes the new Apple iMessage facility which allows you to send messages! Oh no it doesn’t, unless the person at the other end has an Apple device with IOS 5 on it.
I could spend ages working through the various messaging options available to me but it seems whichever I choose I will need to know more about the person at the other end than I actually do. Is Great Aunt Eric on Facebook or IOS 5, does she (or he, I’m not even sure about that) use Google Messenger/talk/chat or whatever it is called?
We now have numerous ways to send messages to people IF we know what THEY use, otherwise it seems we are stuck with a text – I just hope it arrives!