Tip 38: SharePoint 2010 Enable Visual Upgrade on Sites with PowerShell
This tip is for SharePoint Foundation 2010, SharePoint Server 2010 and Search Server 2010 Express.
When upgrading to SharePoint 2010 from WSS 3.0, MOSS 2007 or Search Search 2008 there are some choices on whether or not the administrator wants to upgrade sites to the new SharePoint 2010 look and feel.
If the sites are not upgraded to the new look and feel, there is a way to try out and then set the new look and feel through the site settings page->Title, description, and icon page.
If the sites are upgraded to the new look and feel, there is not a way to go back to the previous versions look through the site settings page->Title, description, and icon page.
There is hope though to go back to the previous version look and feel if it is needed, the SharePoint 2010 Management Shell.
To enable the look and feel choice back to enabled on every site within a site collection, use the script below. Replace SiteCollection with the actual URL for your site collection.
$SiteCollection=Get-SPsite http://SiteCollection
foreach($SPWeb in $SiteCollection.AllWebs){$SPWeb.UIversionConfigurationEnabled=$true;$SPWeb.update();}
To enable the look and feel choice back to enabled on a single site use the following command. Replace Site with the actual URL for your site/web.
$Site=Get-SPWeb http://Site
$Site.UIversionConfigurationEnabled=$true;$Site.update();
Next tip I will show you how you can go back and forth between look and feel versions even on a brand new 2010 site. So if you just love the WSS 3.0 site look you can get that too right in SharePoint 2010.