powershell script to copy mutliple files into a single file

PS C:\temp> $mergeFile = "c:\temp\merged.file" # path/name of your merge file
PS C:\temp> Get-ChildItem -Filter *.txt | foreach { 
  $_.fullname | out-file $mergeFile -Append # append current file name to merge file
  get-content $_.fullname | out-file $mergeFile -Append # append current file content}