data - Historic and future (next) round of machine readable dividend info

Is there a source of historic dividend dates, ex-dividend dates and dividend values? Also, the next dividend date / ex-dividend date.

Ideally in a machine readable form? The publically available APIs don't seem to have the above info as an optional form of info.

UpcomingDividends seems to have some of the future data and Google Finance seems to have the last dividend info (although no date).