My sister was in love with her pacifier--so much so that she ended up having skin discoloration around her mouth. We gradually weaned her off of it and I want to say that she was around 10 or 11 months old but it's been so long ago that I can't remember very well. Anyway, we took it away from her in the day time except for her nap time. When she stopped going hysterical over that, we took it away from her completely in the day time and once she got over that, we took it away from her at night. By that time, she seemed to accept that the pacifier was going away and at each stage, she would become less and less upset until she finally just gave it up.

I needed to know this myself, so I looked around and found the following from this website.  check it out for more info, but here's the bulk of it http://www.cyh.com/HealthTopics/HealthTopicDetails.aspx?p=114&np=122&id=1736

It is best for children if they can give up their comforter when they are ready, not when other people think they should.

• Children do this when the comforter loses its special meaning for them and when they feel confident trying new things (usually between 3 and 5 years of age).
• One and two year olds may agree to give their dummy to the fairies, but they do not understand that they can't have it back when they need it. The child may be distraught when he later needs it and it is gone.
• Nagging about it will make the child more worried and need the comforter more.

When you can see that your child needs it less, you can put the comforter on a shelf when he is playing happily.
 

• You can tell the child where the comforter is so he can get it when he needs to, but it won't just be in his mouth or hand when he doesn't need it.
• Make sure the child is not lonely and bored during the day so he is less likely to think about the comforter.

If a child still needs a comforter a great deal after 5 or 6 years of age, or if a younger child is unable to enjoy play without the comforter being there, it is important to try to find out what is happening in his life and to deal with any underlying stresses.