While running a seniors (over 50) event alongside other chess tournaments doesn't seem to work (at least in my experience as an organiser), running them as a stand alone event seems to attract more players. The obvious explanation is that players prefer to play players of their own strength, rather than their own age. But when there isn't conflicting events, senior players are happy to play senior events.
The New Zealand Chess Federation is currently running the 2010 New Zealand Seniors Championship. However it is doing double duty as the 2010 Oceania Seniors Championship as well. The reason for this is that the Oceania Zone is entitled to nominate 1 official representative for the World Seniors Championship, and having a qualifying tournament is obviously a good way to decide who gets to go. Therefore in the field of 21 players are a few Australians, including top seed FM Brian Jones.
The tournament began today and is being managed by the Canterbury Chess Club. Full results are available from the clubs home page.