Hi. There's a problem with the Solaris 11 virtual machine link. I didn't really know how to notify this (all contact info I found was related to product support).
Anyway, here's the issue:
From www.virtualbox.org there's a link to Pre-built virtual machines at OTN, pointing to http://www.oracle.com/technetwork/community/developer-vm/index.html
In that page, you can download "Solaris 11 Admin VM - Oracle Solaris 11 11/11", but the link is wrong (it's the same as the weblogic developer vm machine): http://www.oracle.com/technetwork/middleware/weblogic/downloads/weblogic-developer-vm-303434.html
I guess it should be pointing to Oracle Solaris 11 11/11 at http://www.oracle.com/technetwork/server-storage/solaris11/downloads/virtual-machines-1355605.html