Looking through the SPModule Powershell Script, I found an interesting comment in the script:

Write-Verbose "You didn't provide a PID Key, looks like I'll have to give you a trial key."

switch ($PhysicalSKU)
            {
                "OfficeServer"   { $CurrentConfigXml.Configuration.PIDKEY.Value = "BR68M-F6WK6-W6BVB-GXQGB-W67BG"  ; Write-Verbose "Using a SharePoint Standard Trial PID Key. You can upgrade to Enterprise trial from Central Admin if you want to."; break}
                "ProjectServer"  { $CurrentConfigXml.Configuration.PIDKEY.Value = "9B4JM-6R6F8-2CMGW-T3T7W-6TYJW"  ; Write-Verbose "Using a Project Server Trial PID Key."; break}
                "SearchServer"   { $CurrentConfigXml.Configuration.PIDKEY.Value = "CX79M-QPKH7-7GFJQ-Y37T4-KKBRM"  ; Write-Verbose "Using a Search Server Trial PID Key."; break}
                "WCServer"       { Write-Error "There is no trial for WCServer, you must specify a retail PID Key."; break}
                default          { Write-Verbose ("Your SKU doesn't require a PIDKey: {0}" -f $PhysicalSKU)}
            }

Here is the evaluation key. Now only the bits have to be released for the public :-)