Our company uses Exchange 2010 and MS Office 2011 for MAC. We have a public folder on the Exchange server setup to be a contacts folder. In the public folder I can see individual contacts but not distribution groups. My coworkers on MS Office 2010 for their PCs have no issues seeing the groups. I know distribution groups in a public folder are not supported in Entourage but I though it would be in Outlook 2011.