Today I used iChatAV to talk to my parents in India. My dad and I have a powerbook G4. He was using the internet service at my cousin's house in Delhi - DSL for $15/month. I was using a cable modem down in san diego CA.
It worked amazingly well! There was no echo very little delay.. and the voice was crisp and clear.. just like having an audio ichat with someone local. A regular phonecall on the otherhand costs a bunch of $$, has a nasty echo effect and a long delay...
Now I wonder how video will work.. Maybe i'll get an isight before i go to india...
That said.. the next logical step is for Apple to make iChat for Windows in a partnership with AOL... meaning that AOL bundles it with the next version of AOL. Just like iTunes helps sell iPods - iChat could help sell iSights..