Invoke-BalloonMessage.ps1

function Invoke-BalloonMessage {
    Param (
        [Parameter(Mandatory)]
        [string] $Message,

        [Parameter()]
        [string] $Title = "Attention $env:username",

        [Parameter()]
        [ValidateSet('none', 'Info', 'Warning', 'Error')]
        [string] $MessageType,

        [Parameter()]
        [string] $SysTrayIconPath = 'C:\windows\system32\WindowsPowerShell\v1.0\PowerShell.exe',

        [Parameter()]
        [int] $Duration = 10000
    )

    begin {
        Add-Type -AssemblyName System.Windows.Forms
    }

    process {
        $global:balloon = [System.Windows.Forms.NotifyIcon]@{
            Icon            = [System.Drawing.Icon]::ExtractAssociatedIcon($SysTrayIconPath)
            BalloonTipIcon  = [System.Windows.Forms.ToolTipIcon]$MessageType
            BalloonTipText  = $Message
            BalloonTipTitle = $Title
            Visible         = $True
        }

        $balloon.ShowBalloonTip($Duration)
    } 

    end {
        if ($balloon) {
            $params = @{
                InputObject      = $balloon 
                EventName        = 'BalloonTipClosed'
                SourceIdentifier = 'BalloonClosure'
                Action           = {
                    $balloon.dispose()
                    Unregister-Event -SourceIdentifier BalloonClosure
                    Remove-Job -Name BalloonClosure
                    Get-Variable -Name balloon -Scope global | Remove-Variable -Force
                }
            }
            $null = Register-ObjectEvent @params
        }
    }
}

# Invoke-BalloonMessage -Message "Test" -MessageType Info