There may be other unforeseen breakage primarily in the handbook portion of the wiki.
The Table Of Contents section of each "PC-BSD® Users Handbook" page may be the best workaround.
Talk:Multiple Boot Environments
Since this feature appears to be cli-only for v9.1, we may not have as much trouble with user confusion. However, once it becomes easily accessible and highly visible, it will get used more frequently and we need to be sure it is understood.
I would suggest that a very descriptive explanation be provided during the first two uses or attempted uses. This may be helpful for cli as well, but I would tend to believe that MBE would remain largely unnoticed except for those who have experience with ZFS (and it may even be new to some of those folks).