Get-MACVendor.ps1

<#
.SYNOPSIS
Find MAC Address Vendors

.DESCRIPTION
Lookup Vendor of MAC Address regsitered on IEEE.org (Institute of Electrical and Electronics Engineers) database

.PARAMETER MACAddress
MAC address to lookup

.EXAMPLE
PS > Get-MACVendor -MACAddress "dc-4a-3e-81-d0-66","d4-81-d7-c4-34-43","48-4d-7e-e6-a8-94"

MACAddress        ManufacturerName
----------        ----------------
dc-4a-3e-81-d0-66 Hewlett Packard
d4-81-d7-c4-34-43 Dell Inc.
48-4d-7e-e6-a8-94 Dell Inc.

.EXAMPLE
PS > "18-DB-F2-48-51-F6","58-FB-84-C1-31-26","dc-4a-3e-81-d0-66","00-50-56-C0-00-01","00-50-56-C0-00-08" | Get-MACVendor

MACAddress        ManufacturerName
----------        ----------------
18-DB-F2-48-51-F6 Dell Inc.
58-FB-84-C1-31-26 Intel Corporate
dc-4a-3e-81-d0-66 Hewlett Packard
00-50-56-C0-00-01 VMware, Inc.
00-50-56-C0-00-08 VMware, Inc.

.NOTES
General notes
#> 
Function Get-MACVendor {
    Param(
            [Parameter(
                Mandatory = $true,
                HelpMessage = 'MAC Address to lookup',
                ValueFromPipeline = $true,
                Position = 0
            )]
            [ValidateNotNullOrEmpty()]
            [string[]] $MACAddress
    )

    Begin{
            $TempFileName =  "$env:TEMP\MACReference.csv"

            If(Test-Path $TempFileName){
                    $Data = Import-Csv $TempFileName
            }
            else{
                    $Data = Invoke-WebRequest 'http://goo.gl/VG9XdU' | `
                    ForEach-Object content | `
                    Tee-Object -FilePath $TempFileName -Verbose | ConvertFrom-Csv
            }
    }
    Process
    {
        Foreach($MAC in $MACAddress){

            $Data.where({($MAC.replace(':','').replace('-','')[0..5] -join '') -in $_.assignment.split(' ')}) | `
            Select-Object @{n='MACAddress';e={$MAC}}, ManufacturerName -OutVariable Output

            If(-not $Output)                                   
            {
                Write-Error "Couldn't find Manufacturer information for $MAC"
            }
        }
    }
    End{
            Remove-Variable -Name Data; [gc]::Collect()
    }

}