The content being offered up, titled The Story So Far, is in preparation for the third season of Battlestar and more or less sums up everything that has happened in the series. There was no concrete date set (but the new season starts in October) or price. We can only hope because it is basically an advertisement, that the content will be free. If it is, we'd say this is a good sign of varying entertainment options being made available to the 360 and Xbox Live.
[Update: NBC Universal reps told GameSpot that the Battlestar Galactica episode would be free of charge and available in mid-September. The rep was unclear as to the size of the download.]