I have a couple of senior portrait sessions set up for this summer. I have never done any portrait work so I need some help. My biggest concerin is knowing how to pose people. Are there any good books, or resources out there that would help me with this? I plan to dig out my high school year books as a starting point.

I plan to dig out my high school year books as a starting point.
No!!! (Running screaming ;) ).

Have some fun with it. Ask them what their hobbies are and maybe use that as an idea to get something a little different. Last weekend, I had a senior portrait shoot with a guy who loves his Mustang convertable. We went to a couple of places to shoot it, including a barely-two lane road out in the country and I laid down on the road for a different perspective (had someone watching so I wouldn't get run over!). I also used a really wide lens and shot him driving from the front passenger seat.

I'm not an expert on posing, but I do have a couple of books on it. I'll let you know what they are tonight. I try to do things a little more PJ (photojournalistic) so they're not so stiff and, well, posed looking - but knowing some basics can really help.