Equivalent of Linux `touch` to create an empty file with PowerShell?

Using the append redirector ">>" resolves the issue where an existing file is deleted:

echo $null >> filename

To create a blank file:

New-Item -ItemType file example.txt

To update the timestamp of a file:

(gci example.txt).LastWriteTime = Get-Date

Here is a version that creates a new file if it does not exist or updates the timestamp if it does exist.

Function Touch-File
{
    $file = $args[0]
    if($file -eq $null) {
        throw "No filename supplied"
    }

    if(Test-Path $file)
    {
        (Get-ChildItem $file).LastWriteTime = Get-Date
    }
    else
    {
        echo $null > $file
    }
}