Live view on the LCD it must be noted, is a giant plus when using a tripod.
The term "P&S" must be defined as most call mine a "P&S". Really, there are very few true P&S cameras anymore. Most of the so called "P&S" cameras do have some limited control up to the complete full control that you have with dSLRs.
Let's start calling them compact, superzooms, and dSLRs from now on

. With compact digital cameras, I have yet to see one with the LCD display in the viewfinder. If they have a viewfinder, they are usually optical, but not through the lens. They are offset through it's own optics and do not give the exact same image as the lens. That said, the majority of compact digitals no longer offer a viewfinder and only offer view with the LCD on the back.
Most of the superzooms do have viewfinders. They are all LCD and offer the view through the lens. Just as dSLR cameras, what you see through the viewfinder on the superzooms is what your sensor sees. It's a toss up about the comment earlier that they lag behind. Some do and some don't. My viewfinder on my Fuji runs at 60 FPS (frames per second), same as the LCD on the back. There is no noticable lag in the picture that you see. In researching cameras, I did see many of them only running at 30 FPS.
When I was looking for a new camera, having a viewfinder was important to me. It's one of the reasons I chose the camera that I did, though the first one I chose when I had a compact in my hand (Canon SD1000) also had a viewfinder, so that didn't hold a whole lot of weight in my decision. Other factors (size and zoom) is what made the decision. I don't think I would be nearly as happy, or doing what I am doing with the camera if I would have gone with one that doesn't have a viewfinder. Originally I was looking for a new family camera, then decided on one with more capabilities than a small camera when I started reading about photography and new I wanted to do a bit more than family snapshots.
The only time I use the back panel LCD is when I have the camera on the tripod.