Not sure about the semantic web as defined but there's quite a bit of metadata in some places. Last time I checked a full tweet was 4kb in size which is quite a

Not sure about the semantic web as defined but there's quite a bit of metadata in some places. Last time I checked a full tweet was 4kb in size which is quite a lot for 140 chars of text :) If metadata is useful it will be used but pre-emptively adding semantic information to everything seems pretty unlikely.