Yes - on the expiry date. However I was told by US Immigration that the system is setup to cancel your Nexus the day before your passport expires if you have not provided them with a new passport expiry date. Nothing to do with how long your Nexus can be active ... it can still be active for the 5 years ... but if you do not provide them with updated passport information (if your passport expires before your Nexus does), they stated emphatically that your Nexus would be automatically canceled.
My Nexus is valid until 2013, however my passport expires in 2009. If I do not provide them a new passport expiry date prior to my passport expiring, it does not matter that my Nexus is valid until 2013, it would be canceled.
They did not do this automatically with CANPASS but appear to be doing it automatically with Nexus.