In the current default skin it's hard to differentiate between one post and another one. My suggestion is to make it easier to know when you pass from one post to another one while reading a thread.
Following reading Brogan's post and screen grab it prompted me to take half an hour playing with with the Style Properties system. It really is just great. I was never happy with the seperation between posts - we went from a pretty much standard style to this, which is much easier to differentiate between posts: