The HFESA has two international conferences organised every year - OZCHI and the HFESA Conference.
OZCHI - This is the annual conference organised by CHISIG (the Computer-Human Interaction Special Interest Group of the HFESA). This conference has recently surpassed it's 20 year anniversary which is certainly a milestone! This conference focuses on Computer-Human Interaction topics, and future uses of technologies.
HFESA Conference - This is the annual conference organised by the HFESA. This conference has a broad focus, and may cover any issue pertinent to Human Factors and / or Ergonomics. For information about the HFESA 2010 Conference: http://burgess-limerick.com/site/HFESA_2010_Conference.html