We've landed the changes necessary for Sunbird to be built as a Universal Binary.
Please enable building as a Universal Binary in the appropriate tinderbox's mozconfig.
K; we'll put this on the list. The problem is the machine that this build is on can't build Universal Binaries; so it's more than just flipping a toggle in the tinder-config.
bm-xserve10 is now building Sunbird as a Universal Binary.
Thanks for your help!