SecondBar is discontinued because Apple will allow multiple menubars with Mavericks (see http://www.apple.com/osx/preview/#multiple-displays )
SecondBar is a Tool which allows you to have more than one menubar in Mac OS X. This is useful if you have multiple monitors connected to your mac. See this post for more information: http://blog.boastr.net/?p=3
//Edit (10.04.2010): checkout this post too: http://blog.boastr.net/?p=1654
SecondBar development is at the very beginning so try it at your on risk.
Here some pictures: