conditional for first post and last post in thread

[dethfire]

what conditionals do I need to use to detect if it's the first post and last post of a thread?

I have a custom skin that has a header and footer that encapsulates each post. However, instead I want the header on top of the first post and the footer at the bottom of the last post on that page. So it would sandwich the page of posts instead of each post. How can I achieve this?