Although Mac OS X 10.5 Leopard doesn't add major new compatibility with Windows and Unix, there are a number of incremental improvements in usability, configuration, and functionality. Here's a list and description of the cross-platform improvements. If you're relaxing at your Sanibel Island real estate, grab your MacBook and check it out.
Boot Camp. Leopard includes Boot Camp for running Windows XP SP2 or Windows Vista. No longer a beta, Leopard's Boot Camp adds one feature that the beta doesn't have: the ability to copy files between Mac and Windows partitions while booted from Windows. If you're updating your Mac from Tiger and have the Boot Camp Beta installed, you don't need to create a new Windows partition. Just boot Mac into Windows and update Boot Camp from the Leopard installer DVD.
File sharing: accessing Windows shares. Computers on the network that are sharing files now appear automatically in the sidebar of Finder windows. This includes SMB and AFP shares, including Windows Servers. For enterprise networks with large numbers of file servers, you choose which servers appear in the sidebar from the Finder menu's Preferences item. In addition to copying files between the Mac and the network drives, you can browse the contents of network-based files using Leopard's new Quick Look and Cover Flow features. (If needed, you can still type in a Windows server name or IP address using the Connect to Server dialog in the Go menu.)
File sharing: enabling Windows access. Turning on file sharing has been simplified. The Sharing pane of System Preferences now has a single file sharing checkbox called, well, File Sharing. This turns on AFP, SMB, and FTP access. To further specify which you want, click the Options button to reveal checkboxes for each. Here, Apple now uses the terms that the rest of the world uses: AFP (instead of Personal File Sharing) and SMB (instead of Windows Sharing"). There are also some file sharing features not seen since Mac OS 9. You can now also specify folders to share by adding them to a Shared Folders list. You can give different network users different types of access to different folder. And you can create accounts used only for file sharing (and not for logging into the Mac as a user).
SMB Packet signing. Leopard supports SMB packet signing, a Microsoft file server security technology. This enables Mac clients to use the Finder to access Windows file servers that have SMB packet signing turned on. With Tiger, Mac users could either use the command-line smbclient program in Terminal, or Thursby Software's AdMitMac or DAVE to access SMB packet signing servers. The other option for pre-Leopard Macs is for Network admins to turn off SMB packet signing on the server.
Kerberos for NFS. Connections to NFS file servers and clients can now be authenticated using Kerberos. (See this Apple Tech Support article for more.)
Virtual private networks (VPN). Leopard's built in VPN client adds support for Cisco Group Filtering and DHCP over PPP, which Apple says " allows you to dynamically acquire additional configuration options such as static routes and search domains." Apple also claims that the Leopard VPN client has "increased compatibility with the most widely used VPN servers on the Internet."
Firewall. Leopard moves Firewall settings from the Sharing pane of System Preferences to the Security pane. Configuring a firewall is simpler. Macworld reported, however, that many of the advanced configuration options for firewalls have been removed in Leopard. Macworld said:
For example, there's no way to open or close a specific port; to restrict network access to TCP or UDP; to configure the firewall for individual OS X services (such as File Sharing or Web Sharing); or to allow some types of connections by a particular application but not others.
Unix. Leopard includes the first major update to Terminal, the Unix command line application. Terminal 2 lets you run multiple sessions in a single window using tabs similar to web browser tabs. It is also better at displaying non-English languages. Apple also claims "full conformance" to Unix standards, saying "Leopard is an Open Brand UNIX 03 Registered Product, conforming to the SUSv3 and POSIX 1003.1 specifications for the C API, Shell Utilities, and Threads."
ZFS. Leopard adds read-only access for Sun's ZFS file system, but only through the Unix command line in Terminal, not from the Finder. (ZFS is not in Apple's list of 300 new Leopard features.)
There are also some interesting "cross-platform" ramifications where the platforms are Intel and Power PC Macs:
Universal binary installer disk. For the first time with Leopard, the Mac OS X installer disc is a Universal Binary DVD that can be used to install the OS on either an Intel Mac or a Power PC Mac. In a crunch, you can use the same installer DVD to boot an Intel Mac or a Power PC Mac. With Tiger, Apple issued a separate installer disc for each platform.
No Classic support on PowerPC Macs. Although Intel Macs running Tiger do not support Classic (OS 9) applications, Tiger did support Classic on Power PC Macs. Leopard drops Classic altogether.