Powershell Script for Setting SharePoint's Developer Dashboard

Here's a script that can be used to enable, disable or allow toggle of the Developer Dashboard in SharePoint 2010. Note that if using the V3 interface, you can customize the master page to add the dashboard control so that it will render:
<SharePoint:DeveloperDashboard runat="server" />

$svc=[Microsoft.SharePoint.Administration.SPWebService]::ContentService

$ddsetting=$svc.DeveloperDashboardSettings

$choiceOnDemand = New-Object System.Management.Automation.Host.ChoiceDescription `
        "On &Demand","Dashboard can be toggled via icon near Welcome Menu"
$choiceOn = New-Object System.Management.Automation.Host.ChoiceDescription `
        "&On","Dashboard is on for all pages"
$choiceOff = New-Object System.Management.Automation.Host.ChoiceDescription `
        "O&ff","Dashboard is off"

$choices = [System.Management.Automation.Host.ChoiceDescription[]]($choiceOnDemand, $choiceOn, $choiceOff)
$caption = "Specify Developer Dashboard Setting for Farm"
$message = "Current the dashboard is: $($ddsetting.DisplayLevel)"
$result = $Host.UI.PromptForChoice($caption,$message,$choices,0)

switch ($result) {
    0 { Write-Host 'Dashboard is now On Demand, toggle via icon near Welcome Menu'
        $ddsetting.DisplayLevel=[Microsoft.SharePoint.Administration.SPDeveloperDashboardLevel]::OnDemand 
        break
      }
     
    1 { Write-Host 'Dashboard is now On'  
        $ddsetting.DisplayLevel=[Microsoft.SharePoint.Administration.SPDeveloperDashboardLevel]::On 
        break
      }
    2 { Write-Host "Dashboard is now Off"
        $ddsetting.DisplayLevel=[Microsoft.SharePoint.Administration.SPDeveloperDashboardLevel]::Off 
        break
      }
      
    default { throw "Developer Error"}
}

if ($result -ne 2) {
  $ddsetting.TraceEnabled = $true
  Write-Host @"
  Trace was also enabled.
  Note: v3 interface requires this on the master page for the Dashboard to render:
     <SharePoint:DeveloperDashboard runat="server" />
"@
} else {
    $ddsetting.TraceEnabled = $false;
    Write-Host "Trace was also disabled."
}

$ddsetting.RequiredPermissions = 'EmptyMask'

$ddsetting.Update()

It also turns on trace, so it can be handy to find hard to debug problems.
In my case, it was helpful to find out why a delegate control wasn't rendering:

Tag(8e1n) Failed to create a user control from virtual path '/_controltemplates/CustomSearch.ascx': 
'Microsoft.SharePoint.WebControls.SearchArea, Microsoft.SharePoint, Version=12.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c' 
is not allowed here because it does not extend class 'System.Web.UI.UserControl'.

Based on approach from Praveen Battula's blog