As a number of you have repotred, Photosynth has had problems handling uploads over the weekend. This got worse about 30 minutes ago when one of our storage systems went offline altogether.
We're working on getting it back up, but until then about 10% of synths/panos will be unviewable, and about 10% of people attempting to upload in the last few hours may experience an error or the "Stuck in Publishing" problem. These should recover when that storage unti comes back up.
Our apologies for the inconvenience. More info coming soon.
Photosynth Group Program Manager