I noticed they are running for StackOverflow.
I also noticed that the previous occured in january this year, does this mean that the next P.SE elections are due in january 2012?
Moderators are elected for indefinite terms and serve at the pleasure of Stack Exchange. Elections are held when there is a need for more moderators, either due to increased workload or moderators taking extended or permanent leaves of absence. From Grace Note on Gaming.SE:
Normally, we hold elections once shortly after graduation, then roughly look into it once a year afterwards. However, this is further refined based on the needs of the site. For example, if the current set of moderators (after this election) is more than sufficient, then we could probably skip a year of elections. Times change and the important thing is to have people who have the available time to spend on the site and cover it well. As such, a lot of elections is about when the site needs it, more than it is any periodic effect. Periodic checks are more as a good habit to investigate whether there is an unspoken need.
For example, the elections on Stack Overflow are to elect four more moderators to supplement the 10 man team they have currently. The last supplemental election was held on Gaming.SE, where they elected two moderators to replace Grace Note (who became a Stack Exchange, Inc. employee) and offset the increased traffic on the site.