Pre-release Update 3 was released on June 14, 2005. Version numbers are:

Kickstart 51.28
Workbench 51.1
U-Boot 1.1.1 (March 2005)

From Hyperion's web page:

The following is a non-exhaustive list of the features of update #3:

• New Kernel. The new kernel includes numerous optimizations, bug fixes and new features. It can now run a special variety of ixemul library and thus run all of the ADE. ELF library has a memory leak fixed.
• New IDE devices. IDE drivers are included for the VIA 686B onboard and Silicon Images 0680 Parallel ATA controllers, and the Silicon Images SiI3112, SiI3512 and SiI3114 Serial ATA controllers. All of these support UDMA on hard disks and CD/DVD-Drives.
• New Picasso96/Graphics and monitor drivers. The new monitor drivers support usage of vertical blanking interrupts for display synchronization. Limited Gamma support is available in the Voodoo driver.
• Warp3D V51. This update contains Warp3D V51, the all new, OS4-native version of the classic 3D hardware driver system. This release includes completely re-written drivers for the Voodoo 3 (Avenger), Voodoo 4/5 (Napalm) and the Radeon 7x00 series of graphics cards. New features include single-cycle multi-texture support (two simultaneous units on the Voodoo's, three on the Radeon) with simplified and extended combiner modes, interleaved vertex arrays, up to 8-bit stencil buffer support (where supported by hardware), and more.
• WarpUp support. The new powerpc.library emulates loading and execution of WarpUp binaries. There are a few remaining compatibility issues, especially in conjunction with Warp3D, that are still being worked on.
• New Shell and updated shell commands.
• Update reaction classes and new intuition.
• New Roadshow TCP/IP stack and updated eth3com.device.
• All new version of the Sirion USB stack and usbprinter.device.
• Updated datatypes.
• Updated Preferences programs.
• Updated Locale.