@Bogdan: I haven't had a chance to track down the problem yet, unfortunately. I just restarted the publish for all of the shops that were stuck in the "publishing" process.
Until I manage to fix the problem, a safe workaround is to just click the "cancel publish" button if you think your shop has been publishing for an excessive amount of time. Then you can re-start the publish process, and it should complete within a reasonable amount of time.
