RE: CIO - for those who have done it
Well, honestly, I wouldn't worry about it with a 6 month old. He still has lots of time to grown and mature. Waking up once to nurse at 6 months is not uncommon. As long as you are not unhappy about it, I would give it time and see if he eliminates that nursing session on his own.
If you want to encourage him to go sleep on his own without rocking, I would occasionally try laying him down in his crib and see how he does. He may surprise you and go sleep. But my DD was sometimes going to sleep on her own and sometimes not at 6 months. It wasn't until she was 7-8 months that she did this reliably (and it is not uncommon for some babies to take later). As long as what you are doing is comfortable for you and your family, I wouldn't worry about it.
HTH,
Beth, mom to older DD (8/01) and younger DD (10/06) and always missing Leah (4/22 - 5/1/05)