I have noticed recently on Steam for a variety of games that they've started to sell something called a "Season Pass".
For an example of some of the season passes I've seen, see the following;
In both instances, these appear to be for future downloadable content which is/are not yet available.
Are season passes in terms of gaming a new thing? Is this something specific to Steam? Is it always essentially pre-selling downloadable content or are there other examples where a season pass for a game provides additional benefits?