Apple offers now a 2TB Time Capsule in the Apple Store (via Engadget) for $499.99
The Time Capsule, a wireless hard drive that works seamlessly with Time Machine in Mac OS X Leopard. It’s also a full-featured 802.11n Wi-Fi base station with simultaneous dual-band support.
Apple updated the Time Capsule in March with simultaneous dual-band Wi-Fi.
I just started to configure a 2TB Buffalo TeraStation III for backup and single vault for media files. This NAS actually supports RAID 5 and houses four 3.5 inch HDDs.