I've heard of two separate ways to use a water bath when cooking a cheesecake: placing the cheesecake in the waterbath, or placing a roasting pan full of water on the bottom rack of the oven, with the cheesecake on the top rack. I like the idea of not putting my cheesecake in the water, which avoids the need to wrap the pan in foil. Do these two separate methods create any discernible difference in the final result? Is one better than the other? 
I have to disagree with Sobachatina in this case: the thermal mass is not the sole purpose of the water bath. Cheesecakes are prone to cracking, because the moisture of the outer layer of the filling evaporates. They don't just form a skin the way a standard custard would, they get dry enough to crack later.   So, if you just suspend the cheesecake, you get half the benefits of the water.   It is entirely possible to bake the cheesecake without submerging it, or without using any water at all. But you will get better results with water than without, and you will get better results if you submerge than if you just suspend. You have to know for yourself whether the difference is large enough to matter to you, and whether the convenience gain would be worth it.  