Lost in all the hubbub about Wednesday's Power Mac G5 announcement is that these new Power Mac G5s will be the first to contain an upgraded Setup Assistant application that will transfer your files and preferences from your old Mac to your new one, reducing one of the big hassles that comes with moving to a new Mac.
Of course, back in the days of Mac OS 9 you could just mount one Mac's hard drive on the other's desktop and copy all the files over. But with OS X's directories full of invisible Unix files, things have gotten a lot more complicated. I've taken to using Carbon Copy Cloner every time I migrate from one Mac to another.
This new feature of Setup Assistant requires that your old Mac have a FireWire port and be running at least Mac OS X 10.1. Then, when you load up your new Mac for the first time, you'll be asked if you want to copy information over from your old system.
At the beginning of the process, Setup Assistant instructs you about how to put your older Mac into FireWire Target Mode, by restarting it with the "T" key held down. Once the two computers are connected via FireWire, Setup Assistant scans the the old computer's drive and presents a panel with several options about what to move from old Mac to new.
Among the items you can opt to move are user accounts and the corresponding user folders (you can copy them all over or choose them on a per-user basis), network settings, the contents of your Applications folder (although it won't bother copying old versions of pre-installed software if there are newer versions present on the new G5), "Files and Folders" (essentially anything that's on your drive in someplace that's not a standard system directory -- for example, stuff that's in a folder you created at the root level of your hard drive), and the contents of hard-drive partitions that aren't the old Mac's boot partition. (My understanding is that the contents of other partitions are copied to the root level of your new Mac's hard drive.)
Once you've chosen what you want to copy, the new Mac begins the process of transferring all the data over via the speedy FireWire connection. Once that transfer is done, Setup Assistant continues the process of getting your new Mac configured -- but now with the knowledge of the new accounts and settings that have been transferred over from your older system.
Transferring the data isn't a use-it-or-lose-it option, either. Since Setup Assistant is an application on the new Mac's hard drive, you can also choose to run it at a later time and add in your old accounts, settings, and documents when you're ready to make the move.
( Updated June 10, 12:44 pm PT, with information from Apple. Thanks to MacFixIt for the initial tip. MacFixIt's article now also links to a series of screen shots that show this feature in action.)