Bryan claims to have seen a steam engine last night on the Aizu Wakamatsu train cam. Doing a little more research, I came across an article (PDF) that provided some basic background information.
This 4-6-2 Class C57 retired in 1969 but was restored this year by JR East’s Omiya Works. It will be run on the Banetsu West Line between Niitsu and Aizu-Wakamatsu on most weekends from May to November. There will also be some runs between Koriyama on the Tohoku shinkansen and Aizu-Wakamatsu.
Update: For those interested, a tour is available from the UK.