On page 74 of the ebook, you'll find a description of the Time Capsule. Earlier this week, Apple began shipping a new, dual-band model of the device, which offers two important new features that you should be aware of when deciding if the Time Capsule is right for you:

• The Time Capsule now has two Wi-Fi radios built in, making it possible for it to offer networking on two different bands at once. So, for instance, using a new Time Capsule, you can run an 802.11g network for iPhones and older computers, while also running an 802.11n network for newer computers and an Apple TV.
• The new model offers a new guest networking option wherein guests can log in to your network via a special password (or no password) and thereby access the Internet, but not other devices on your network. So, your guests can go nuts with YouTube, but without also being able to use up all the ink on your printer.

(Note that the new model of Apple's AirPort Extreme Base Station, also made available earlier this week, also supports these new features.)

—Posted by Tonya Engst on March 5, 2009