For anyone using the MultiSelectField (http://silverstripe.org/multiselectfield-module/) module, I've just submitted a patch to trunk which allows it to be used in the main SiteTree admin area as well as front end and modeladmin. I wasn't actually aware that it didn't work in the SiteTree admin until Aram pointed it out, as I've never had to use it there! Get it here:
Silverstripe trunk tarball may take a while to catch up.
Provided I don't get any more reports of problems, I will add a 0.3 release shortly.