Upcoming.org is a site Yahoo bought a while back. It's social networking, etc. based around shared public events.
...and they're going to get nowhere with that site. Digg, reddit and del.icio.us dominate already and Yahoo isn't creating anything new worth switching to.
Wait doesn't del.icio.us belong to Yahoo already? If that's the case - everything's clear, they're just trying to eliminate extra competition...