I am super excited you can now download a compiled version of OpenSolaris that includes the new ZFS Dedupe support! However when I went to try installing build 128a from GENUNIX, I found it kernel panic’d on both VMWare Workstation and ESXi 4.0.
A little googling and I found this bug and workaround:
6820576 Kernel panic when booting Nevada and OpenSolaris http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6820576 When booting build 121 on a VMware guest instance, the system may panic with the following function listed in the kernel stack trace pcplusmp`ioapic_read Work-around: Boot with the "pcieb" driver disabled by editing the GRUB "kernel$" entry. This can be done interactively by typing the character "e" when the GRUB menu appears and using the arrows key to navigate to the "kernel$" entry. Entering a second "e" will allow one to append to the end of the line the string " -B disable-pcieb=true". To complete the boot, enter a carriage return followed by the "b" character. To make this change persistent, edit the file /rpool/boot/grub/menu.lst and add the same string to the appropriate "kernel$" entries.
That fixed the problem right up thankfully!