Starting at 3:00am US Pacific Time, and extending for about 9 hours thereafter, a small portion of Photosynth uploads have failed. On the iPhone you see "Network Error", and on the desktop you see the progress meter fail to advance in the "publishing" phase. This affected about 200 synths/panos.
If this happened to you, you will need to re-upload. On the desktop, you'll want to repeat the "Synth", and on the mobile client you should press "retry" 5 times to clear all state.
David Gedye and the Photosynth Team.