Next month, Dell Inc. is putting a second hard drive in new machines that will automatically back up what you're doing on your main drive by mirroring it. You can recover something you inadvertently erased, for example. The company also says the backup can roll back the computer to a time before, say, you were infected with a virus. (And it would presumably work better than a similar feature in Windows, which works only if you keep setting days and times for it to recognize. It works poorly enough that I don't want to get into describing it in detail.)
The extra drive will come as an 80GB drive with $599 desktop systems. That sounds like a deal and may be a worthwhile investment for business, if the other parts of the system are what you want and need. (I back up onto an external Maxtor hard drive, and may sometime soon subscribe to an offsite backup service as well.) Dell says backups to laptops is coming soon.
News.com also has this bit on an Intel storage product that could be used for backup.