[Centurion2000]

For example, if a Mohamed Atta associate is being searched, and the key evidence is in a Palm Pilot he can smash at a moment's notice,

Bad example, you'd be amazed at what FBI data recovery specialists can get off electronics. You can shoot the hard drive and they will still get it.

[FBDinNJ]

Yeah if I ever had to dispose of a computer hard drive that the FBI was looking for I'd be sure to douse the thing in gasoline, set it on fire, smash it a few times with a hammer and then go and bury it in the woods, in the hope that they would never find it in the first place.

[strela]

You can shoot the hard drive and they will still get it.

Anything short of using a couple of thermite grenades on it would still leave plenty of data to be recovered.