So with the whole emergence of web 2.0 there has been a great deal of emphasis on making web applications behave much more like desktop applications. Now integral to this process has been Ajax, and this has of course opened new possibilities in User Experience, so much so the line between web application and desktop app has blurred significantly, and these types of applications are now being referred to as Rich Internet Applications (RIA).
However as rich as the UE gets, there is still the issue currently of storage. That being that the majority of RIA's are render useless when there is no internet connectivity. However this problem is starting to be addressed and there are 2 major milestones that have appeared recently to highlight this fact.
1. The Dojo Offline Toolkit. This project is designed to allow users of the well know Dojo library to be able to work with local storage
2. Firefox has now got offline cache support checked into its code trunk. This will make Firefox 3 very appealing for RIA developers.
Also working heavily in this area are Adobe and their soon to be released Apollo which is getting some serious hype.
I think it is going to be interesting to see what Microsoft do in this area, whether it be within the asp.net Ajax framework,within IE itself or for me the perfect solution would be to build offline storage/cache as part of wpf/e.