I found it interesting that Mark sees Mashery as a potential "brokerage" for web services. We tend to use the term "marketplace" rather than "brokerage", but under either nomenclature, we do our best to discourage the notion that web services access will be "sold" in the conventional sense (such as on a CPM basis). The vast majority of the most successful APIs we see generate revenue indirectly - through additional traffic from links, through additional user signups, by selling more of the underlying service, through a revenue sharing arrangement, etc. It is the rare API that (a) has inherent value; (b) is unavailable in a free or indirectly monetized form; and (c) free of the risk that unexpectedly high usage could result in unpredictable costs for the developer paying the bill. In our view, all of those are necessary features of any API that will attract any significant direct revenue over the long term.
So we use the term "marketplace" to mean a place where developers can come and find the various building blocks they need to quickly and economically deploy Web applications, without the implication that they will use them on a "pay as you go" basis. The API providers will still generate a lot of revenue from their APIs, but Mashery's role will likely be more as a means to promote broad distribution, manage the chaos that would result from an API free-for-all, and provide the tools and reporting needed to determine the success (however each API vendor defines and measures it) of each API offered through our infrastructure.