I am currently raising a litter, and since it may be the only breeding I'll ever do in my career I'm taking a very methodical approach, guided by a professional canine behaviorist (Janece Rollet - faculty member of Karen Pryor's trianing academy)
We started the litter with the old military "Bio-sensor" or "Superdog" exercises, a series of five simple exercises that are repeated once each day during the first 13 days of life. You can see a video we created of the process at
http://s273.photobucket.com/albums/jj224/Swanny1790/?action=view¤t=NeonatalPuppyTraining.flvThose exercises are done in addition to the daily handing, cuddling and 'loving up' that we do with any puppies (and in fact all the dogs in my kennel).
Now that they are older they are handled as often as possible, and are being introduced to as many people and exposed to as many different situations as we can create. This will continue as a concentrated effort through the first 16 weeks of life, and then will be casually maintained throughout the remainder of the lives.
Here are two very good articles on puppy socialization.
The first discusses the science behind the process -
http://www.apbc.org.uk/article5.htmThe second describes the recommended process -
http://www.apbc.org.uk/article6.htm
“A good dog is so much a nobler beast than an indifferent man that one sometimes gladly exchanges the society of one for that of the other.” ~William Francis Butler