By 12noon Pst on Oct. 31st if you own the Binding of Isaac on Steam, you will get this....
BIG HALLOWEEN UPDATE (with no actual lame halloween themes)
-Added chapter 5 (unlocked after 10 mom kills)
-Added 3+ new bosses
-Added 4 new enemies
-Added 20+ new items
-Added one new unlockable character (Eve)
-Added one new "FINAL" ending.
-Added 6+ new achievements
-Added 2 new music tracks
-Added updated collection viewer
-Added 4 new tarot cards (finishig the major arcana)
-lots of small bugs were fixed
-load time fixed
-a few minor item balances
Also this is the most amazing Isaac fan art ever! Thanks @LeePfenninger