Any time data coming in from the middleware or database will have offsets. Any time data going to the database must also include ISO offsets. Make sure the middleware handles this correctly. Be on the lookout for ad hoc time conversions between UTC and PST/PDT in SQL queries. I believe this was done in the ADU processing. If found, remove the conversion as the new tz aware timezones will do the right thing on their own.
Search makes no conversion on dates, but is broken by Peter's work on bug 713927. It will be easy to fix. Report/list do make a conversion in it's PHP version. The middleware version is ready and waiting on that UTC problem to be solved, but reconsidering it I think it should land with our UTC release. See bug 678642 for details. TCBS should be fixed by Josh's work on the matviews. Nightly builds report uses only date (and not datetime) so there should be no problem. Current versions seems fine too, there's no date argument. That's it for services I know about. Lars can you look at adu and email stuff please?