It is too soon to tell
It has not (yet) been resolved, the device is too new and frankly the killer 3G version has not yet been shipped. It is not known whether native apps (iPhone type apps developed using Objective C and Cocoa) or Web apps (like Google Docs and Calendar) will dominate in the iPad world.
A lot of folks are assuming that iPad utilization will be like IPhone utilization with folks using native apps predominately on the iPad, like folks do on the iPhone today. I think this will be the case in the short term, as these devices are viewed as big iPhones in the iPhone paradigm.
I am not sure that is the case for the long term, though. Just because the device runs the iPhone OS does not mean these are iPhones. Perhaps the iPhone paradigm will dominate when the devices are used for content consumption (like books, movies and the like.)
But, I also suspect you are going to see more folks using these devices as thin clients in a cloud computing model. The larger screen enables much more functionality for using Web applications in the cloud (with local caching, like Google Gears.) Ubiquitous connectivity using 3G + WiFi makes it practical.
That is why I am waiting for the 3G model. Comparing an iPad with WiFi to one with 3G to me is like comparing an iPhone to an iPod touch. In my opinion, it will not be long before a WiFi only iPad is considered pretty lame.