(Still not sure what's going on? Launch the Calendar app on your iPhone, tap the Calendars button in the top-left corner, and look at the headings on the resulting Calendars screen. If you see one entry for From My Mac and another that includes your MobileMe address--, for instance--you're duplicating your efforts.)

But suppose you have different events in the calendars you synced from your Mac and those that are synced via MobileMe and you'd like all of your events on the iPhone. What to do? Try this:

Attach your iPhone to your Mac and in the Info tab disable iCal syncing. When offered to keep or remove the calendars currently on the iPhone, choose to keep them and click the Apply button at the bottom of the window. Now move to your iPhone, choose Settings -> Mail, Contacts, Calendars and select your MobileMe account. Flick the On/Off toggle next to Calendars to Off. Again, you'll be offered the choice to keep or delete your calendars. In this instance, delete them (don't worry, they're stored in the cloud). Now switch this Calendars toggle back on. In the sheet that appears, tap Merge.

What happens? The duplicate events currently stored on your iPhone (the ones synced from your Mac) and on MobileMe will be merged into a single event. Any additional events not found in your MobileMe calendar will be added to MobileMe.

Did I mention that Apple's syncing strategy needs a stern overhaul? Let's hope the iCloud rumors are true and we get exactly that.