I have my work email up an running on my iphone (and have since 2.0 came out).
My company forces the auto-lock to be on (longest setting is 5 minutes) and the it prompt for a four digit code when waking it up if it has been asleep for 15 minutes (longest setting).
This was all fine and dandy under 2.0/2.2/etc.
Now, with 3.0, I can still set auto-lock to five minutes which is fine (a bit annoying when developers of games and music streaming applications don't include an option to override the lock, but its fine to deal with), however, the passcode lock is now set to immediately. Its not really a big deal to enter a four digit code, but now I have to do it every time the iphone wakes up. Put back the 15 minute option please apple.