It looks like the Storage Spaces feature of Windows 8 will be very powerful.
Fundamentally, Storage Spaces virtualizes storage in order to be able to deliver a multitude of capabilities in a cost-effective and easy-to-use manner. Storage Spaces delivers resiliency to physical disk (and other similar) failures by maintaining multiple copies of data. To maximize performance, Storage Spaces always stripes data across multiple physical disks. While the RAID concepts of mirroring and striping are used within Storage Spaces, the implementation is optimized for minimized user complexity, maximized flexibility in physical disk utilization and allocation, and fast recovery from physical disk failures.
My family have been using a Data Robotics Drobo device for more than six months now and it's been very successful. These types of low-end, easy-to-use, simple solutions for home storage are wonderful; it's great to see that Microsoft will be providing this as part of their core operating system.