If you have had any personal contact with anyone in the program (prof, admissions coordinator,etc.), I would e-mail that person. If not, then take the name you found listed. Your e-mail should just be a few sentences, for example:
Subject: Checking In
Dear So-and-so,
I am writing to inquire about the status of my application for Fall 2010 admission into the ____ department. (The next sentence explains why you want to know now -- e.g. perhaps you are being asked to let another school know of your decision to attend, or you're anticipating changes in housing plans next month, or you're just so excited about their program, or ...) I will be leaving (my current school) at the end of the month and I am now making arrangements for the summer. I would appreciate your letting me know the Admission Committee's timetable and when I might hear from you regarding my candidacy.
Thanks in advance for your earliest reply.
Kind regards,
Summerbreeze
Good luck!