Microsoft OWA Calander Sharing

We just recently migrated from Notes to Outlook and are using OWA for many of our employees who so not have actual desks or computers (such as many of our nurses, etc). One of the apparant limitations we are getting complaints about is that OWA does not allow the use of shared calanders, which is import to some groups within the hospital. Does anyone know if there is a way to support this for OW users? Or has anyone found a workaround or 3rd partty solution to this issue? thanks!