The discussion seems to have died out. I've bumped the thread.
Thanks!
Currently, it's possible for (receiving) addresses to not be in the address book at all. Those are considered change addresses by the wallet interface. I don't think that's exactly what you need, since deleting an address on which you've received money would confuse the user interface.
It's close, but not exactly what is needed.
Effectively, the only thing it has to do is hide the address in the UI. Internally, nothing special has to happen, and the address should still be in the address book for lookup purposes.
The current proposed wallet encryption patch will use the default address for generations, if no fresh pool key is available. I doubt it's necessary to show this in the user interface, though. It seems like a legacy way of showing people "this is the address you should use".
OK, seems it was a good idea to hide it from the user interface then.
Update: - CSV export of the transaction history has been implemented. Up next: address book export.