From personal experience I've never had any trouble taking shots with my DSLR but of course only once the cabin crew have been cleared to leave their seats. I wouldn't really want to take a shot before as the crew are sat in their seats for good reason.
If you are going to take a shot in flight your point and shoot will be ok but to get good pics you need a polariser on your lens to remove cabin reflections.
Good luck with your shots but always make sure to play by the rules!
