I recently tried installing both OpenSolaris and Nexenta Core Platform on a Dell PowerEdge 2850 with a DRAC4 card. The installation process goes fine, but when rebooting into the installed OS the kernel goes into a loop of trying to reset an ATA device (‘Bus Reset’ errors — if I have a chance, I’ll repeat the process and get the exact errors.) I finally just disabled virtual media (go into the DRAC setup menu by hitting Ctrl-D on bootup, hit page-down, and use the ‘E’ option to turn it off), and after doing that, it worked just fine.
Annoying error (it’s odd that the installer works fine, but then the actual OS doesn’t; possibly because there’s no CD ‘inserted’?), but at least it’s not too hard to work around.