Yes, although this is rare, it usually just means that you need to wait. Back when Photosynth was brand new this was more common, but I think that all of my synths that got stuck have showed up. It tended to take a day or so, though.
Retrying the synth is probably the quickest way to see results and you may find that in doing so, you end up pushing the 'stuck' synth through.
For the Photosynth team, the synth that I left going overnight is also stuck in Publishing after being cut off the first time yesterday by the maintenance session.