If you use Excel 2002 or later and have function tooltips enabled this is pretty much the same thing in a more compact display.
This comes in handy when you're several levels deep in a complex formula by letting you know which function you're providing the arguments to.
On a related note, Excel 2007 and later has a formula auto complete feature that lets you select the functions from a drop down list. Personally, I hate this and disabled it but you may find it helpful.