One thing I like about having an iPhone is that everything is kept in sync with my other devices via MobileMe, including bookmarks. I keep my most frequented websites in subfolders on the bookmarks bar (where, by the way, any new articles in RSS feeds show up as a handy little number next to the folder name). You can imagine the irritation I felt when I noticed that only my Safari bookmarks outside of subfolders were syncing. All those frequently used bookmarks? Conspicuously absent.
Scouring Google revealed no one else having a similar problem. Apple troubleshooting mentioned overwriting info on MobileMe with info from your computer if no bookmarks are syncing. Not exactly my problem, but tried it anyway. Availed not.
But where the internet failed, random fiddling came to the rescue! Here's what I did to get my bookmarks bar folders (and all other subfolders) to sync.
In Settings, open Mail, Contacts, Calendars and select your MobileMe account. Turn off Bookmarks syncing, and delete previously synced MobileMe bookmarks from the iPhone. Give it a moment to process the action (I jumped out to Safari to check that everything was deleted), then turn Bookmarks syncing back on and voilàeverything was as it should be.
I would guess this will probably solve other sync issues as well, so give it a shot if you have any troubles.
And for the record, I absolutely hate spelling "synch" without an "h." Synch. Synching. The "ch" makes a hard "c" sound. I guess I should be glad it doesn't have a stupid lowercase i in front of a capital S.