I have done something similar at my site, I had created the conference rooms as if they are users mailboxes, and I have given select people the Editor permission to the calendars. the only trouble I have had is if someones clock is off on their computer, the times are off when they reserve the conference rooms because they do an "open special folder" to access them, and it uses their computer times to display the calendar. I hope this helps.
List Charter and FAQ at: http://www.sunbelt-software.com/exchange_list_charter.htm
