As we move to using login.launchpad.net as the primary means of authenticating to Canonical/Ubuntu/Launchpad related sites, we'll have more sites that pull profile data from the OP.
At the moment, the only way to edit this data is for the user to go to their Launchpad profile page. For users who are not Launchpad users this is not obvious. It should be possible for a user to go to https://login.launchpad.net and change their details.
Assuming that the user is already logged in, a minimal implementation would be to provide a link to the appropriate forms on https://launchpad.net. If the user isn't logged in, we would need to authenticate the user first. Bug 176845 would take care of this.
Better would be to actually host the edit forms on login.launchpad.net itself, which would help users associate the site with management of their identity.
Notice that I can't edit my address information (the one I used for ShipIt) going to my Launchpad profile page.