Seriously though, if I thought that Netapp hardware was the kind of thing that would "go up in a puff of smoke" from something as simple as an incorrect disk drive, I never would have let it in my server room in the first place. These are well-built robust machines. In my experience, they're not going to go tits up over something as basic as that. I can't envision anything bad happening worse than the disk just not being used. This isn't like a plain old scsi bus where connecting a device incorrectly can short the whole bus out (I've scene a couple of sparcstations die that way). These things are designed to be hot-swappable. If the disk is for some reason the wrong size or manufacturer or type, it will a) probably not even fit in the shelf, or b) just not get recognized by the filer.
If there's some great risk of plugging in an unknown disk, I'd like to hear about it.