All of my iCal events have been duplicated, I deleted the duplicated ones and then iCloud deleted the originals! I've now got to re-key them all...
This just feels like Mobile Me part 2 - no mail al day, calendars broken... perhaps it's my own fault for being an early adopter but did nobody test this? I know you can't really test for the extraordinary server loads experienced but duplicate iCal events? How did that not appear in testing.
Okay, rant over, feel free to down-vote me.
That was your fault. You deleted the wrong thing. If you looked at the calendars section you'll have seen the MobileMe calendars were still there with the iCloud - hence the duplication. All you needed to do was go into the accounts setting of iCal and remove the MobileMe account...
But you decided to delete all the iCloud calendars instead...DOH.