No, it's bad for their teeth because the liquid can pool around the teeth. Going to sleep with a breast in their mouth actually doesn't harm the teeth at all (the milk angles past them towards the back of the mouth instead), but a bottle is different. They also can't control the flow of liquid with a bottle and I would worry about it being a SIDS risk.
With Justine on this one. Not a good idea. Not only could they choke, but they may get use to having the teat in their mouth, which could mean big problems if and when it falls out. And by big problems I mean they might wake up! I don't know about others, but when we first brought our son home from the hospital, I would get incredibly anxious listening to him through the monitor when he was sleeping. I would think 'Gosh, please don't wake up yet. Sleep. Sleeeep.' That, plus you may have problems weaning them off it or with tooth decay.
I'd say its a big no, but I've got friends who swear by it to get their kids to sleep. For me, I'd be concerned on the bottle being a choking hazard or that they'd possible choke or vomit on too much milk. I'd also be concerned with the baby getting too attached to the bottle and then its another comforter that once it goes missing in the night you'd have to go and find it etc. it's a personal choice but I'd be thinking of safety first.
This is a complete no-no. Not only a choking hazard and dependency factors but also very detrimental to development of jaws and tongues. In addition, it causes problems with eruption of teeth and further tooth decay.