In his latest blog posting, The Service Repository Concept is Incomplete, Nick Malik suggests the creation of an exchange site, onto which service consumers could post a specification of the services they want. Similar demand-led exercises were also proposed for component-based software engineering. I wrote something in the CBDI Journal back in October 2000 about the Job Bid Market. More recently (April 2004), Lawrence wrote a review of TopCoder, which has an effective Job Bid Market, and a very precise specification process.This is a very attractive idea, for many reasons. However, one of the problems with the Job Bid Market - whether for components or services - is the lack of precision and richness in specification. Without machine-readable precise specifications, the transaction costs are likely to be prohibitive.
Specifications need to include semantics as well as commercial considerations. Some of the characteristics of Web 2.0 may be relevant here, including user-defined semantics.
Pricing is also interesting. Nick suggests that consumers can indicate how much they would pay. But does this result in everyone using a service paying a different amount - like passengers on an airplane? Or is there some complex auction system where every consumer willing to pay more than X ends up paying the same X? There are some Web 2.0 possibilities here as well.