Apple is not talking with Verizon about the iPhone – AT&T will keep its exclusive deal for a while. But their new tablet (see my post “Apple’s Next New Device – the NetPad!“) is another story.
I believe the tablet, or NetPad, as I call it, is like a larger iPod Touch, with one major difference. It will have the ability to connect to various cellular data services like AT&T, Verizon, and T-Mobile to transfer data across the Internet. Like Amazon’s Kindle, will not make voice calls, just transfer data. AT&T will keep it’s exclusive for voice, and therefore for the iPhone. But the data-only NetPad, that’s a new ball game.
With this in place, the NetPad, like the iPhone, will be able to connect to the Internet over WiFi where available, and the cellular network everywhere else.
So, no voice calls over the NetPad. But what about VOIP calls over the Internet? Well, Apple currently allows VOIP only over WiFi, and not over the cellular network. I expect this will continue.
That’s why Apple is talking to Verizon. The GSM version of the NetPad will connect with most carriers including AT&T and T-Mobile, while the CDMA version will connect to Verizon. I expect Apple might be talking to T-Mobile soon, and all these talks are to set up data-only connection rate packages for the NetPad.

I think you make a good point, it would certainly solve the problem I have with my iPod touch where I can only use it in wireless connections.
I hope they make this feature optional though so that you aren’t forced into a data contract if you don’t want it.