The semantic Web took center stage Friday afternoon at the Web 2.0 Summit in San Francisco, with officials from three companies showing wares in this vein.According to Wikipedia, the semantic Web serves as an extension to the Web in which content is expressed not just in natural language but also in a format that can be used by software agents that can find and integrate information easier.Presenting on the semantic Web were Radar Networks founder Nova Spivack; Danny Hillis, CTO of Applied Minds, and Barney Pell, CEO of Powerset. Spivack introduced a service called Twine. “Twine is a new service for the end user side of the semantic Web and what Twine does is it ties it all together and helps you use [information],” said Spivack, describing the application as knowledge networking.Twine learns about a user’s interest and recognizes people, organizations and concepts. Twine uses natural language understanding and builds profiles of a user and his or her interests. A user can take an object such as a flickr photo and “twine it,” in which a semantic Web of data would be organized about the image. A twine also can be started for a team or a group. Radar has been approached by banks, media companies and others that want to use Twine as a new way to manage knowledge, Spivack said. The company is about to proceed with an invitational beta program on the application. Hillis showed an application called Freebase, which is in an alpha stage of release. It opens up silos of data and creates interconnections between them, he said. “What Freebase is about is a database that has all kinds of data in it and an API that can be used for lots of other applications,” Hillis said. Freebase is a platform specifically designed to be used through other applications that take advantage of the data in it. At Powerset, the company is building a search based on keyword technology, creating a semantic index. Every single page is read sentence by sentence to create this index, said Pell. For example, a user could search on wrestler Hulk Hogan and find out the kinds of things Hogan does, such as who he has defeated, Pell said. Powerset also is in an early release stage. Software Development