It is true that applications like Photoshop and CAD will be incredibly difficult to implement within a web capable container, but do we really need that? I have never used either application and I do not believe either rank highly as an everyday tool for most people running around in big businesses.

The benchmark for web applications will always be Microsoft Office or rather, the fraction its functionality that is genuinely useful to a large number of users. Once you have a web-delivered application that delivers that sort of feature set, then a totally web-based desktop environment becomes a very practical option.

Ajax (Asynchronous JavaScript and XML) is the ultimate web programming methodology for producing dynamic, rich web experiences - it is one of the hottest technology topics around today, and it can be used in conjunction with all of the major server-side development tools, including Java, PHP, ASP.NET, etc.