Holger Biebrach created a simple little tool for OSX called render status mailer, which will email a notification with or without a preview image or movie of your render once complete. The application watches a folder for completed renderings, so it works with any application that you are rendering with.
“Have you ever finished your weekend with a really bad feeling in your stomache because you where not sure if the Rendering you started on Friday was successful? Render Status Mailer helps you out. It sends you frequently Emails about the Status of your rendering and a preview Image attached. If the Rendering is done, you will recieve a compressed Movie-File of your Animation ready to watch on your Iphone (for this Feature you need Quicktime Pro).”