Feature: Time Machine
How it works: Plug an external hard drive into your Mac and Leopard will automatically detect it and ask if you want to enable the Time Machine back up option. Select yes, and you're done. Time Machine will automatically back up your entire hard drive but if you want to skip certain files or folders, simply tell it what to do in the preference pane.
Time Machine is also handy for that dreaded "Why did I hit delete?" moment. If you accidentally trash that presentation you've been working on the night before you need it, just flip back through the files on the back up drive until you find what you need. Apple assumes that this will happen to everyone at some point, so they'll thoughtfully provided access to Time Machine right in Finder.
Got more than one Mac? No problem. Multiple machines can be backed up onto one drive via your wireless network.
Who will use it: Anyone who hates losing files, folders, documents, or media unexpectedly. So, pretty much everyone.
More Q&A on Time Machine at our earlier post here.