First and foremost ask for a business card of the interviewer. This allows you to get the title and spelling correct for your thank you note. (my name isn't all that tough to spell, so it drives me nuts when it is spelled incorrectly)
Send the note the day after the interview thanking them for the time and reiterating any points you made about your experience and qualifications. Quote something back to them about something they said, so they know you were paying attention.
State in the thank you note your "next step" intentions. For example, "I will call you in a few days to see if you have any followup questions." or "I look forward to meeting with the department Vice President."
Close with a professional "Sincerely,"
I tend to type thank you letters, because I have miserable handwriting, but I don't think it matters. If i were to handwrite a note, I'd use nice stationary (Cranes makes really nice monogrammed note cards) Use good quality paper, not just plain old paper.
Googling a bit, this site has some pretty good examples of thank you notes
http://www.quintcareers.com/sample_t...u_letters.html