I'd say it's one of the oldest technologies, so old that we don't even look at it as a technological product anymore. But no super-fast almost-intelligent intel-based mac could be safe without it....From a MAC101 post:

Whether your Mac asks you for certain information or you're seeking help from Apple or an Apple Authorized Service Provider (AASP), there may come a time when you need to have your various passwords, dial-up numbers, mail server addresses, email addresses, hardware specifications, serial number, and other information handy. And then you discover that you've either forgotten or misplaced this information.

If you forget it, don't sweat it—pull up your Mac Cheat Sheet instead.

To make your Mac life a little easier, we created this little form for you (or your Mac-savvy family member or friend) to enter all that easy-to-forget information once, and then stow it safely away should you ever need it. Just download the PDF document below, print it out, fill out the fields with your information, and store it in a safe and secure place.

Download My Mac Cheat Sheet