Here are a couple of listings for the summer season from usahostels.org:

Massachusetts, USA
  • Hostel Manager - Truro (Cape Cod, Massachusetts) - Full-time (40hrs) seasonal (June-September 2008)
  • Desk Staff and housekeeping - Eastern New England Council of HI-USA, Cape Cod & islands, Massachusetts - Seasonal (May – October 2008 – varies depending on location) - Housing Available