If you're building projects with Maven, you're most likely building Java projects, or projects that heavily use some parts of the Java platform, and you're likely familiar with longer builds.
If your project takes more than a small number of seconds to build, there's a significant chance that after triggering a build, you switch your attention to something else -- you check your email, you read news, you do something to pass the time. If your build fails quickly, you might not notice the failure for several minutes because you're busy looking at something else. Accordingly, it's helpful to get notifications that can let you know that the build is complete or has failed, so that you can get back to the task at hand, building software, as soon as possible.
On the OS X platform, if you want to send a notification, far and away the most common system for doing so is Growl. There are no Maven plugins for sending Growl notifications (although apparently the Maven 3.x shell has integrated Growl), so I built a simple script to bridge Maven with Growl, and built a couple simple images to use in the notifications.
The {{gmvn}} script can be used to invoke maven, and based on the exit code from Maven, invoke a failure or success notification.
The {{resources}} folder contains the icons I've used in notifications, which were exported from the {{maven-growl.psd}} photoshop file.
I haven't officially put together any kind of license for this. It's safe to say that I have no plans to exert any kind of control over this. If it's useful to you, feel free to use the script, the images or the photoshop file, even if you plan on using it commercially. If it breaks your code, reformats your hard drive or burns down your house, I take no responsibility and offer no warranty.