How can I recursively delete folder with a specific name with PowerShell?

This one should do it:

get-childitem -Include .svn -Recurse -force | Remove-Item -Force -Recurse

Other version:

$fso = New-Object -com "Scripting.FileSystemObject"
$folder = $fso.GetFolder("C:\Test\")

foreach ($subfolder in $folder.SubFolders)
{
    If ($subfolder.Name -like "*.svn")
    {
        remove-item $subfolder.Path -Verbose
    }       
}