Perhaps I'm being optimistic here, but generally servers will be built with the operating system and drivers on a separate hard drive array and the data on another. This sort of setup should enable restoration of sites easily. Further, I would assume the hosting company maintains regular backups of the data on yet another system.
Fingers crossed and maybe we'll be lucky.
I would say that regular backups by forum administrators is also a good practice unfortunately I am totally guilty of failing that on my own boards so I'm not gonna say nothin' about that!