Steppemums' contributions, esp. on the "other practices in other countries" thread is really interesting. I think she said where she lives (Asian Steppes) that the babies sleep in cots with a whole in the bottom area for the mess to pass through while sleeping, but she's not sure how city dwellers do it, or how anybody manages in the cold! She's also a bit unsure how it's going to all work at the Mum+Tots group she is starting.
We just found a "Women's" magazine jammed in the wall that appears to be date from about 1960... it has a Q&A section including "After many months of being good My 18 month old suddenly refuses to sit on the potty"... Advice duly follows, mostly about berating the poor thing into submission. I reluctantly believe you can potty train from very young, but like Mears said, I have better things to do with my time, and I rather suspect it's most successful with lots of bullying & punishments (Steppemum talks about that, too).
Mind you, The "ECT" brigade would claim that they are just pursuing a state of being more in sync with their child's needs, and that bullying and scolding are unnecessary...
If very early potty training is so easy & natural and wonderful, how come my Bangladeshi-born neighbours all gleefully use disposables until 2yo, viewing them as one of those wonderful luxury benefits that comes with living in the rich west?????