Several people on my daily blog run are talking about Universal Personal Proxy (UPP) and Web Intermediaries. What they are talking about is an old idea that probably got started when the Web was first invented. IBM Sash is almost exactly what they are talking about. Sash uses JavaScript and DHTML so web developers don't have to learn new languages like Python. It has a cool IDE for writing weblications. There is even a Linux port of Sash. What really intrigues me is why it hasn't taken off.
First off, a typical user has no idea what it is, where it is, and how it does what it does. A powerful bundle of functionalities means little when it has no space in the user's mind.
Second, transition between a user to a developer is too sharp. One has to download a large toolkit and myriads of extensions. Web developers need only a text editor and a FTP client. Even Python comes with mostly everything in one download.
Third, there is no synergy between weblications. Having one thousand individual services is less attractive than ten related services that fits within a single paradigm.
There are other problems I see. Later perhaps.