When I look at the Mash-up I really don’t know how “they?” will solve all these Issues.
When everybody is allowed to program and connect everything with everything a Mash-up will certainly turn into a Mess-up. Many years from now a new Software Lecacy Problem will become visible.
There is one simple way to solve this problem. Somebody in the Internet Community has to take care of this. It has to be an “Independent Librarian” that controls the libraries and issues a Quality Stamp to the software (and the content) that is free to reuse. I don’t think anybody will do this.
Personally I think the Mashup is a very intelligent trick of big companies like Microsoft, Google and Yahoo to take over the control in software development. In the end they will control all the libraries and everybody has to connect to them. Perhaps we even have to pay to use them or (worse) link to the advertisement they certainly will sell.
To stabilize the software development environment we had to introduce many Management Systems like Testing and Configuration Management to take care of Software Quality.
The difference with today is that the software libraries are not internal libraries. They are situated at the Internet.
It took a very long time to stabilize the software development environment. In the very old days programmers were just “programming along”.