O'Reilly Previews Freebase ("appears to be a bastard child of wikipedia and the Open Directory Project")

Disclaimer: I admire Daniel Hillis greatly, perhaps irrationally.

That said, Metaweb sounds amazing. If it takes off, it will be not so much a useful product in itself, but an enabling technology for an entirely new class of products. Imagine the possibilities that arise from having a relatively complete, constantly evolving ontology of everything. All of those nifty tricks that computational linguists and proof theoreticians can do over finite domains, using very limited ontologies, become possible for all sorts of other applications. Armed with an ontology that closely matches the real world, it is finally possible to write code that can reason about the real world, rather than just throw Bayes law at it and hope something useful falls out.