[4] During the five years of development, purchasers of AmigaOne machines could download pre-release versions of AmigaOS 4.0 from Hyperion's repository as long as these were made available.

Nevertheless, AmigaOS 4.0 was released commercially for Amigas with PowerUP accelerator cards in November 2007[6] (having been available only to developers and beta-testers until then).

Also, a third party bootloader, known as the "Moana", was released by Acube on torrent sites; it allows installation of the Sam440ep version of OS4 to Mac Mini G4s.

The Workbench is the GUI of OS4, a graphical interface file manager and application launcher for the Operating System.

Workbench 2.0 improvements introduced a lot of major advances to the GUI of Amiga operating system.

The Workbench was no longer tied to the 640×256 (PAL) or 640×200 (NTSC) display modes, and much of the system was improved with an eye to making future expansion easier.

[18] Unlike the previous versions which were based on the Motorola 68k central processor, OS4 runs only on PowerPC computer systems.

This requirement was overturned in the agreement reached between Amiga, Inc. and Hyperion in the settlement of a lawsuit over the ownership of AmigaOS 4.