Update: Developer Mossmouth Games (read: solo developer Derek Yu) has confirmed Spelunky 2 is coming to Steam. A release date has not yet been announced.
Spelunky 2 was announced during today's PlayStation Paris Games Week livestream. As you can imagine, it was announced specifically for PlayStation 4, but given Spelunky's history and origins, the sequel is a shoo-in for PC.
Apart from the trailer above, we don't know much about Spelunky 2. Though we do at least have one big detail: you play as the child of the protagonist of Spelunky 1.
In any case, more Spelunky is good news. There's a reason we rated it number-one on our list of the best indie games to play right now.