There's also some new cookie information, but I'm not sure it's relevant/nontechnical enough to stick in an FAQ.
As a side note, it's really easy to grab diagnostics for request ICs. :)

"You now have separate "www" cookie (your ljmastersession) and per-user cookies, which are per-domain and/or per-path for, say, communities and underscore users.
Also, you can now track your logins:
http://www.livejournal.com/manage/logins.bml
Eventually we'll do things like let you name IP addresses ("Work", "Home") and show in red things that are out of the ordinary, etc. Also emails on new logins that aren't in your whitelist."
Edit: Could be useful information in Request 550357 and Request 550443. Should also do something with FAQ 66 on Comment IP Logging.