In Mountain Lion, many of the day-to-day apps like Preview, TextEdit have been upgraded with some very useful features. (For instance, you can now insert a page into a PDF document using your scanner in Preview - see here, and pinch the trackpad for zooming in on to a document - see here). However, as far as I understand, these apps are free, and features like these are features of the app themselves, not the OS.
Is there anyway in which I can replace/upgrade individual apps in Lion, without having to install it as a whole (preferably as a dual-boot config!) ?