The panel has been responding to two questions: What’s been important in making the blossoming of mashups possible, and what are the barriers?

Andy says, Ajax has been key, but had been around for a long time. He notes that it emerged from an enterprise context, but was simplified for use in the consumer world, and is now making its way back into enterprises.

Shawn Burke says the sheer proliferation of services has been important, but what's really driving interest in the mashups is consumers who desire to create their own solutions. The more the mashups happen, the more consumers become interested in exposing their own data. New client technologies like Silverlight, Flash and even Ajax are enabling a new burst of mashup creativity. Another enabler is the fact that the pieces (e.g., YouTube) are getting bigger and more therefore more useable.

Mike notes that REST, iFrames and XMLHTTPRequest have been important drivers and are winning the day over more elaborate initiatives such as WS*.

Aaron says let’s just stick with standards, such as HTTP, JSON, XML, Atom.

What’s holding back mashups? Where are things falling down? Aaron says it's hard for him to be pessimistic since everything seems to be coming together. Pressed on where he's had to "hack around" a service endpoint to make it work, he smiles and says Windows Live has been difficult. “We don't need new standards,” he says, “we just need to continue using the ones we have.”

Mike says mashups are one "ginormous" hack. The big challenge in the end is security. He likes the idea of declarative controls to determine what data gets sent where.

Shawn notes he works for a company that sells tools. He sees REST as a problem because it's hard to build tools for REST endpoints.

JSON is great for communicating state, but it's scary that you're sending code across the internet without confirming that it's only state. The lack of a unified way to identify web services and determine what they offer is his nut to crack. Andy says standards for how gadgets communicate with each other would be valuable.

Aaron believes many business have invested in SOA, but have not seen a return on their investment because there's no way to tie those services together.

A questioner notes the gap between the simplicity of the tools that users are being given -- such as Yahoo Pipes and Popfly. Andy says a really interesting market is that of Excel users who are not developers, but are somewhat technical. If someone gets a tool right for that audience there's millions to be made. Popfly requires someone write a wrapper in order to make a service useable.

Another panelist says the mashup tool for the masses is the classic portal -- such as Pageflakes or iGoogle -- where a user can aggregate feeds, mail, weather gadgets and more.

But what about the elephants in the room: Facebook and OpenSocial, as the ultimate mashup tools?