Of interest to those who no longer have control of a) the original address on their LJ accounts, b) those who have hotmail addresses associated with their LJ accounts that they no longer control...It appears that you can now remove those addresses.
FYI, and get on that, folks.
(I had *three* addresses I no longer controlled on there, which are thankfully gone now. Apparently in 2002-2004 I was quite the web-based e-mail whore.)ETA:
It doesn't appear to be available to everyone, and as noted in comments below, this *does* leave open another huge security hole. So, I suppose, if you're able to remove inaccessible e-mail addresses from your account, do it while you can because the change might be rolled back.