In his book "Mobile as the 7th of the Mass Media" Tomi Ahonen has an interesting description of how the cellphone (I would call it 'the mobile device') changes the way people use the Internet: It moves the experience from 'being networked' to 'being connected'. It totally applies to me.
When I think back to the early days of the Internet, I was indeed networked: I specifically sat down in front of a computer to access the Internet, i.e. to get to my e-mails and to search for information. Once I got up and left the place, I was disconnected. Yes, I was networked, but not all the time.
Today, I don't go to a specific place anymore to access the network. Today, I have a mobile device and it is always connected to the Internet. I no longer open an Internet session and close it, it's just there all the time. I don't log on to check for my e-mails, an indication is already waiting on the idle screen when I look at it. When I search for something, I don't log onto the Internet and start the browser. The phone is already connected to the Internet and the browser is waiting in the background to be used again. And for that matter, so is my social network, the news and all those web 2.0 applications that allow me to see things created by my friends at the other end of the planet just seconds ago and let me put my pictures and content online as well for them to see. And all without sitting down and logging in. For me, the 'net' has become omnipresent, I am logged on 24h a day.
I haven't mentioned voice telephony so far specifically but that's because for me it's just an application running over the Internet as well these days. While I still use the circuit switched cellular network a great deal for voice calls, I most mintues are via Voice over IP now. Thanks Nokia for the great SIP implementation in the N95, it saves me a ton of money for those international calls.
But beware, being connected 24h a day does not mean that I am reachable for everyone 24h a day as well. It's a big mistake people make on both sides of the equation. Some think that once your are always connected you must be reachable. Others think you are forced into it and are thus trying to avoid it. I don't think so and I don't live it that way. With profiles that can be changed with the press of a button I decide who can reach me and who can't.
So I guess here's the difference for me between today and the past: In the past I had to decide when to connect. Today, I have to decide who can reach me at what time. I rather prefer it that way.