@erickerl - Thanks for letting us know, I'll let John comment on that one, the OS X stuff is his baby. Frustrating for those of you affected I'm sure.
I will add that the other packaging issue of 32-bit Sigil and launching from the Open With plugin in calibre still exists with this release as well. So I have just pushed a new version of the Open With plugin to workaround the problem. Please do install that and you won't see the error dialog appearing before Sigil starts any more that was reported on the last thread.