I'm still an email nut with work related stuff but text comes in a close second for work and personal. I'm never in front of 1 computer enough to do the messaging thing unless BBM or I happen to have it open on my phone.
Thinking this through and looking at how fb intends to integrate this messaging, it's sorta already been done with BlackBerry. My inbox integrates with my email accounts, text, BBM, Google Chat, Facebook, Twitter, Linked In (even myspace if you still use it). Anyone using any of these services can message me and it's in my inbox. You don't need to open an application to read and respond. From what I'm reading - this is what fb is looking to accomplish.
Clay, how can phone calls come before email? LOL - I use YouMail to transcribe my voicemails to text email. I have not listed to a voicemail in over 2 years.
We still have a long time before email goes away. But in 15 years - who knows what we will be doing. I know I'll promise my children I'll keep up with the latest communication trends though.