Can old wallpaper be painted over?

Can a wallpapered wall be painted without the wallpaper bubbling/blistering? And if so, what is the best way to do it?

I think the key is to prepair the wall-wallpaper before painting.
Here are some step by step instructions on how to paint over wallpaper:
http://www.diynetwork.com/how-to/how-to-paint-over-wallpaper/index.html

When we moved into our house, all the walls were papered. We couldn't afford the cost of getting it stripped & dealing with the problems which more than like lay beneath. So they were all pained over & all were fine. If any of the paper is lifting, paste it back down beforehand. If any is ripped, sand it down abit first - you won't even notice it in a week or two.

At this stage, most of the rooms have about 10 coats on them!!

I have successfully done it several times, and the link posted by Cat101 tells you all you need to know, really.