VoIP and mobile communication cut the cable that tethered us to the ground. "Where are you?", "Are you still there?" or "Who else is there?" are often the first words uttered in IM and mobile phone conversations these days. Physical presence and Places as an object of socialty can help us contextualize our relationships and communication in an untethered world.

Felix Petersen will talk about the ingredients to the physical presence soup:

• Collaborative mapping of location through widely deployed infrastructures such as LANs and cell towers
• Open standards for describing places for location to become context
• Solutions for privacy and stalking issues by introducing the concept of spacial fuzziness
• Development tools that ease integration of locational context into social and communication software

He will introduce these concepts with the Plazes platform as an example. He will also demonstrate how the Plazes developer kit and introduction of Microformats make it easy for developers to bake physical presence into their services and applications.