Ok, having lifted the lid on this can of worms it looks like edits will be required to:
ADSIProvider.vb - FillUserInfo (get the field values)
Authentication\UserInfo.vb - to store the new fields
Users\UserProfile.vb - to present the new fields
and either
Controls\Address.ascx - to display new fields
OR
a new control ExtendedInfo.ascx - to display new fields
and an edit of admin\users\manageusers.ascx to include ExtendedInfo.ascx
This however will result in a DNN install which is very much hardcoded to my specific network/domain. I can't help feeling there's a missed opportunity here to make this more dynamic and have the AD fields and UserProfile configurable to map to each other.
Anyone know if there is a feature of aspnet membership that I'm missing and could make use of to make this more maintainable/dynamic/reusable ?
Or if there is a way to make better use of the <Profile><Properties> section of web.config with regard to AD and/or Profiles ?