In my case, searching for my network name in Keychain Access brings up 2 items, one in my System keychain and one in the iCloud one.

Both of them end up displaying the raw password on the detail view now, though I do indeed remember that a year ago I saw some wireless passwords being in hex instead.

I'm not denying they might be reversibly-encrypted (although this doesn't happen to me anymore for some reason), but in any case for a WPA(2)-PSK network the key cannot be hashed using a one-way irreversible hash because it is needed as-is to actually complete the authentication. What you're seeing is encryption and not hashing.