I came up against an issue mounting via nfs from a Linux host to an OpenSolaris virtualbox guest (see this post for automounting nfs on OpenSolaris). Checking the host's logs revealed the issue: mountd:  [...] refused mount request [..] illegal port.

This is seemingly caused due to the natted connection between guest and host. Adding (insecure) in the host's /etc/exports line for this export enabled the guest to successfully mount the nfs share.

Upgrading to the b122 bits on my laptop resulted in a kernel panic and reboots upon boot attempt. See this bug: http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6875025

My work-around for this is to boot into my working BE (b121) and do the following:

beadm mount b122 /mnt

copy from /kernel to /mnt/kernel these bits:

/kernel/kmdb/amd64/sata
/kernel/kmdb/sata
/kernel/misc/sata
/kernel/misc/amd64/sata

and these:

/kernel/drv/amd64/ahci
/kernel/drv/ahci

then:

bootadm update-archive -R /mnt

My system then booted successfully to b122.