The USPTO and EPO have agreed to create a new Cooperative Patent Classification (CPC) based on the IPC. You can read the press releases here and here. The new system will be based largely on ECLA, the European version of the IPC, but incorporate the best practices of the U.S. Patent Classification system.
The IPC was created in the 1960s as a common classification system intended to replace the numerous national patent classification systems then in existence. The official treaty creating the IPC system, the Strasbourg Agreement, was signed in 1971. There are now 61 countries party to the agreement. Few national classification systems are still in use. The Canadian Patent Classification system was abandoned in the early 1990s.