I was going to post a blog entries and realized that the example I wanted to give used some of my utility functions so I'll share them first.  I hope you find them interesting.  I put them in a file called LibraryTime.ps1 and dot source that during my login.  BTW  - everyone should adopt that pattern.  Files that contain functions meant to be dot sourced into another script should be called LibraryXXXX.ps1

function Measure-TimeSpan([TimeSpan]$Span, $Units=$Null)
{
   switch ($Units)
   {
   "Weeks"        {[Int]($Span.TotalDays / 7)}
   "Days"         {[Int]$Span.TotalDays}
   "Hours"        {[Int]$Span.TotalHours}
   "Minutes"      {[Int]$Span.TotalMinutes}
   "Seconds"      {[Int]$Span.TotalSeconds}
   "MilliSeconds" {[Int64]$Span.TotalMilliSeconds}
   "Ticks"        {$Span.Ticks}
   default        {$null}
   }
}

function Measure-Since([DateTime]$Time, $Units=$Null)
{
   $Since = Measure-TimeSpan $([DateTime]::Now - $Time) $Units
   if ($Since -eq $null)
   {
      throw 'Usage: Measure-Since -Time <DateTime> -Units ["Weeks","Days","Hours","Minutes","Seconds","Milliseconds","Ticks"]'
   }
   else
   {
      $Since
   }
}

function Measure-Till([DateTime]$Time, $Units=$Null)
{
   $Since = Measure-TimeSpan $($Time - [DateTime]::Now) $Units
   if ($Since -eq $null)
   {
      throw 'Usage: Measure-Till -Time <DateTime> -Units ["Weeks","Days","Hours","Minutes","Seconds","Milliseconds","Ticks"]'
   }
   else
   {
      $Since
   }
}

Set-Alias MSince Measure-Since
Set-Alias MTill  Measure-Till

Now let's try them out:

PS> "weeks","Days","Hours","Seconds","Milliseconds","ticks" | 
>>    %{ "{0,16} $_" -f (Measure-Since "12/25/2005" $_)}
              38 weeks
             267 Days
            6398 Hours
        23034210 Seconds
     23034209798 Milliseconds
 230342098115960 ticks

PS> "weeks","Days","Hours","Seconds","Milliseconds","ticks" |
>>    %{ "{0,16} $_" -f (Measure-Till "12/25/2006" $_)}
              14 weeks
              98 Days
            2362 Hours
         8501789 Seconds
      8501788713 Milliseconds
  85017886963120 ticks

Enjoy

Jeffrey Snover [MSFT]
Windows PowerShell/Aspen Architect
Visit the Windows PowerShell Team blog at:    http://blogs.msdn.com/PowerShell
Visit the Windows PowerShell ScriptCenter at:  http://www.microsoft.com/technet/scriptcenter/hubs/msh.mspx

PSMDTAG:DOTNET Datetime