[peterb]

AFP and CIFS are network file sharing protocols. CIFS is closely related to (or might be the same as) SMB (server message nblock protocol) which has an open source version called SAMBA.

Apple's current operating system is *nix based (open BSD) and therefore will include SAMBA as standard, allowing it to communicate with other servers (windows or *nix based) that use the SMB/SAMBA protocol.

Therefore, provided the Apple has Samba correctly installed and configured, almost any true NAS (as opposed to directly attached NAS, which may use its own proprietary protocol) should work quite happily with an Apple machine.