One of the things you can do with a landline phone you can't with a cellphone is quickly decide whether you want to take a call, or send it directly to voice mail. Verizon has made a computer program that allows you to do just that as a Verizon residential customer. Leave it on, and at the same time your phone rings a little window pops up on your screen with Caller ID and some buttons to allow you to say what to do with the call, including a button to block a number from calling you forever. Add a webpage that integrates an address book and a calendar and lets you manage and email your voice messages, and you have got iobi. Now your home phone can be slightly more convenient than a cell-phone with an address book and a calendar built in.
I am especially intruiged by the integration of having the Caller ID pop up on your desk and allowing you to manage the call from your home desktop computer real-time, as your home phone is ringing. Expensive office switchboard phones allowed you to do that, but the 12 button keypad UI on the home phone did not. Now here it is.
I predict this will be really really useful for people who work at home, but I do not see it taking off as a must-have, even for 'early adopters'. Not at 8 bucks a month.