Active Directory has changed forest functional levels every few years with each iteration adding new features. One of the new features with the 2008 R2 functional level (if enabled) is the Active Directory Recycle Bin. This functionality was available before with the use of LDP and ADSI Edit however the process for restoring accounts has gotten much easier.
Import-Module ActiveDirectory
Get-ADObject -filter {SamAccountName -eq "mydeleteduser"} | Restore-ADObject
Compared to the multiple steps before this is pretty simple.
Now lets attempt to restore a previously deleted computer. First step, get the GUID value
Import-Module ActiveDirectory
Get-ADObject -Filter {(isdeleted -eq $true)-and (Name -like "My_Desktop*")} -IncludeDeletedObjects
Now lets restore the computers
Get-ADObject -Filter {(isdeleted -eq $true) -and (ObjectGUID -eq "Whatever my GUID Value is")} -IncludeDeletedObjects | Restore-ADObject -TargetPath "CN=Computers,DC=liquidobject,DC=com"
Now the computer has been stored to the built-in computers OU.