Vault is a Permissions & Economy API to allow plugins to more easily hook into these systems without needing to hook each individual system themselves.
Vault currently supports the following: Permissions 3, PEX, GroupManager, bPerms, bPerms2, SimplyPerms, DroxPerms, zPermissions, rscPermissions, KPerms, Starburst, iConomy (4/5/6) BOSEconomy *6/7), EssentialsEcon, 3Co, MultiConomy, MineConomy, EconXP, eWallet, CurrencyCore, XPBank, CraftConomy, AEco, SDFEconomy, TAEcon