In the absence of a 'killer' app, it looks like IMS will quietly replace standalone and disparate systems that are currently deployed over some time. We believe its not a 'killer' app that is going to drive IMS deployment, its going to be a 'killer' business model.
The latest generation of cell phones, (like the iphone) , has made web access much easier. Deutsche Telekom reports that iphone customer data downloads are 30 times greater than their other cell phone users. IMS is the vehicle whereby those mobile browsers can be delivered with location aware content, especially as they go from wireless to wi fi and back. What this means is that instead of competing on price in a maturing market, wireless service providers can now take what they know about the user (and where the user is!) and go after some of the advertising revenue opportunity. For example, information about the closest gas station or restaurant.
This web interface, group and presence arms race is already on. Google is bidding on wireless spectrum and developing an open os for handsets, they see very clearly that the carrier has a lock on the user and his location and they are trying to break that lock.
When it comes to 'killer' business models, it is like pushing the steamroller down the hill. Look at what just happened when Verizon came out with a new price plan that drives a new business model. Within 8 hours their two major competitors had matched it!