When talking symmetric encryption, a 56 bit key is known to be so weak. If you use it for your encryption, you are considered a goner.
When talking passwords however, the standard these days is about 8 characters selected from about 94 characters on the keyboard. This translates to about $94^8$ possible passwords, which means about 52 bits of entropy.
Now, 52 bits is obviously less than 56 bits. But somehow a 56 bit key is considered weak while a 52 bit password is considered safe (i.e., many systems force you to use the 8 characters). Why is this so; I mean why are the standards lower when we talk passwords yet both passwords and keys are subject to the same kinds of brute-force attacks?
I know that humans would find it impossible to maintain a 128 bit password -- however, I wonder if there is some technical reason why a 52 bit password would not be as weak as a 52-bit encryption key for that matter.