We are a Apple/Linux shop here with a couple of hundred employees. We use Active Directory (switched from LDAP) and we have the Macs on load sets. We recently outsourced our email to Google. It is not as easy as with Windows.
Microsoft has a good thing going in enterprise as their boxes are much easier to manage en masse and it works well together. I do not think they are threatened as much by cloud services like Gmail, Google Docs as much as people think. They simply say to their entrenched enterprise customers in which things are working for them "We offer cloud Exchange and cloud Office" I think MS has the enterprise community on lock and they are moving in the direction to transition them to online services.
Microsoft has a good thing going in enterprise as their boxes are much easier to manage en masse and it works well together. I do not think they are threatened as much by cloud services like Gmail, Google Docs as much as people think. They simply say to their entrenched enterprise customers in which things are working for them "We offer cloud Exchange and cloud Office" I think MS has the enterprise community on lock and they are moving in the direction to transition them to online services.