What's New in Mac OS X 10.3 Panther
Disclaimer: although I am an Apple Certified Trainer by day, this guide is not endorsed by or affiliated with Apple in any way, nor is it indicative of future Apple Training courses. It is based entirely on my own personal experience and research. Any inaccuracies are my fault. Comments and corrections welcome at firstname.lastname@example.org.
Networking: the new Network pane
Mac OS X 10.3 has native support for IPv6. Also, the Network pane of System Preferences has had a minor facelift.
The first thing you'll see in the Network pane of System Preferences is the new Network Status pane, which lists all your network ports, modems, and VPNs. Each port has a human-readable description of its current status; for example, for my built-in ethernet card, it reads "Built-in Ethernet is currently active and has the IP address 192.168.1.3. You are connected to the Internet via Built-in Ethernet." Double-clicking on a network port allows you to configure it, at which point things should look essentially the same as Mac OS X 10.2.
One new convenience feature in the TCP/IP pane is a "Renew DHCP Lease" button, which does exactly that. In Mac OS X 10.2, you could force a DHCP renewal by setting TCP/IP networking to Manual, clicking "Apply Now", then setting it back to DHCP and clicking "Apply Now" again. Now it's a one-click operation.
IPv6 is supported and turned on by default. You can click "Configure IPv6..." and turn it off, or configure it with a static IPv6 address.
The built-in ethernet port now has an "Ethernet" tab for tweaking low-level settings like speed, duplex, and MTU.
Network Utility, the ever-useful network troubleshooting utility, now has an additional tab for troubleshooting Appletalk networking. You can display throughout statistics, view your computer's Appletalk PRAM settings, and browse Appletalk zones.