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I'm really glad that HAL adds the sync option for hotplug media e.g. memory sticks. Since I discovered that, I've happily been plugging media, writing files, and unplugging without unmounting (as you can do without problems on a lesser OS!). However, recently I wrote some files to a Rio Carbon MP3 player, which has an internal 5GB HDD. I unplugged it without unmounting, and then thought I'd better plug it back in and make sure there was a sync option it /etc/fstab. There was not. After some digging I found out that sync (and noatime) is added only for drives < 2GB in size. I think this limit is too small. I understand that for "real" USB drives, you shouldn't unplug without unmounting -- but all consumer electronics devices should have sync in the options, or people are going to end up with corrupted files. (I haven't determined yet whether or not I have corrupted anything on the Carbon by unplugging in a mounted state.) I don't know what the best fix is, but perhaps raising the limit to 40GB would eliminate most MP3 players/cameras (present and near future) from having problems. The biggest players I know of are 20GB. Mind you, there are handheld video players with bigger drives in the works. Perhaps it would be better to have the user manually disable sync for any hotplugged drive they don't want the option on, rather than automatically disabling it based on disk size.
BTW I also suggest there is a problem setting a limit like 2GB, otherwise the user has to think, "OK, this drive I have plugged in is 4GB, which is bigger than 2BG, so I have to unmount first before unplugging". This is even more complicated than users having to remember, "OK, this is seen by the OS as a drive, even though it's external, so I have to unmount before unplugging". Non-oldtime Linux users have trouble with the unmount concept in any context.
First of all, you should always use unmount; using sync and noatime is a stopgap fix. Second, for using the sync and noatime mount options, you may manually create a .fdi file in /usr/share/hal/fdi/95userpolicy to achieve this for your device(s) - for guidance, see this file /usr/share/hal/fdi/90defaultpolicy/storage-policy.fdi and this article http://www.redhat.com/magazine/003jan05/features/hal/#fdi Some day this will be configurable from the UI (could be: right click drive in Nautilus, select "Optimize for fast removal" or "Optimize for performance"), until then I refuse to raise the limit in the default install. Sorry.