How to Reset All SP 2010 Site Pages to Default Definitions with PowerShell

I couldn’t get this to work for me (maybe I was having a thick day) so I asked Colin to devise a way that worked in my situation).  If you need to whack your SharePoint 2010 on the head with a big bat and make it forget all the customizations that have been perform on page and site definitions, then this is the script for you.
Replace the http://portal.somewhere.com/ part with your root site collection and Execute from the SharePoint-enabled PowerShell command line:

$site = Get-SPSite "http://portal.somewhere.com" 
$sites = @(foreach ($web in $site.AllWebs) { 
$web | Select-Object -Property Url
Write-Debug "Resetting all pages in site ($($web.Url))..."
$web.RevertAllDocumentContentStreams()
$web.Dispose() 
}) | out-File -filepath "c:Output.txt" 
$site.Dispose()

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, “Courier New”, courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

It will also output a list of the webs that were bonked to the file c:Output.txt.

Hoping the above helps someone, when they absolutely need to hard reset to definition, particularly in an ugly/adopted site collection migration scenario. (I won’t go into the gory details of the one I had the pleasure of doing)