Get-FullURL.ps1

<#
.Synopsis
   Expands a shortened URL to its full URL
.DESCRIPTION
   Expands a shortened URL to its full URL
.EXAMPLE
   Get-FullURL http:/bit.ly/12345
#>
function Get-FullURL
{
    Param
    (
        [Parameter(Mandatory=$true,
                   ValueFromPipelineByPropertyName=$true,
                   Position=0)]
        $url
    )
    (Invoke-WebRequest -uri $url -MaximumRedirection 0 -ErrorAction Ignore).Headers.Location
}

Fixed trailing space