There is a brief story yesterday in the USA today explaining how ETF dividends work.
In addition to trading on exchanges like stocks, ETFs also share other features. The process for paying dividends is just like stocks: there is a date of record (the date in which the owners of the shares who will receive the dividend are determined), an ex-dividend date (the date an ETF is traded without the benefit of the current dividend is attached to the share), and a payments date (dividend is paid).