Banknotes have been added in an attempt to replace emeralds. Use /withdraw (amount) to create a banknote. Use /deposit (or right click while holding) to deposit back into your account.
This definitely looks interesting. Is there any commands to exchange 5 emeralds for a banknote of 5 (without the emerald exchange at spawn)? EDIT: So what happens to the emeralds you gain from the anagram game? BAI1
Those are just emeralds as we're going to re-enable villager trading. No way to exchange emeralds as of yet, though.