DD is 3 and a half, been dry (with accidents) since 2.3, completely Ok during the day for the last 3 months or so.
She wakes up with a wet pull-up every morning, even when we've lifted her at our bedtime. So I've just decided to wait until she's going through with dry nappies, and I'm not at all worried about it.
She has, this evening, decided nappies are for babies and is going without! She's got up to wee four times already 
I was planning to wait till she's asleep then put a nappy on her. But has anyone's child suddenly 'decided' to be dry at night and succeeded?