Smart Mobs quotes Jyri Engestrom about his start-up:
It’s a social phonebook that displays the real-time availability and location of your contacts. We call this rich presence.
With the Jaiku mobile application, you can share your location (neighborhood, city, country) based on cell tower positioning; your availability (based on whether your phone’s ringer is on or off); an IM-style presence line; current and upcoming calendar events; people and devices nearby (based on Bluetooth scanning); and how long your phone has been idle.
You can share this information with your contacts’ mobile phones. You can also create a badge for your blog, MySpace profile or any other Web page that shows your real-time presence on the Web.