If you haven't heard, ArcPy is the new geoprocessing module that will be out with version 10 of ArcGIS Desktop.
ArcPy has some great new features, especially if you use eclipse to program in python. It is intellasense capable, which makes programming nice and easy. It is also a well organized set of functions with libraries, class, functions, etc... Basically it follows OOP patterns.
What I don't like, is the case sensitivity. This can get annoying, since I'm a lazy programmer. Really, who has time to be pushing that shift key and another letter on the key board?
I think the future looks bright for ArcPy, but only time will tell.