And me again. :) Why break her of it? What exactly makes it so terrible that she is still using it?
To speak of my own experience again... my daughter was 2 years and 3 months old, when my son was born. She still used a bottle at night for her milk. She'd lie on the living room floor to drink her milk, then brushed her teeth and went to bed.
When my son was born, the bottle really turned into a bit of a comfort thing with her. She liked being a baby for a little while longer. When he was about a year old, both kids gave up their bottles. Sure, my daughter was three at that point. But really... nobody asks my now 8 year old, when she stopped using a bottle (or when exactly she was potty trained for that matter).
Take care... and more importantly, take it easy. Our little ones have an entire life to be grown ups. Give them time to be babies.