I have had a similar problem with iCloud synchronisation for a week or so - but not with email push.
The calendar updating between my iMac, iPhone and iPad stopped synchronising (it appears that some calendar updates went from my iPhone to my iMac but not to my iPad - calendar updates on my iMac did not show up on my iPhone or my iPad).
I think the same thing was happening to my Address Book - but I did not test it scientifically.
I avoided using iCloud for email from the start (and did not use iCloud predecessors).
I tried out Andrewita's suggested steps (see contrbution above dated Jun 12 2012, 2.06am) amended for Address Book instead of Email - this involved deleting the entire address book and then having it reload after resetting the iCloud settings. Hooray - this worked allowing two-way automatic syncing of iMac and iPhone Address Books via iCloud. I hope this continues.
I then tried Andrewita's steps to reinstate synchronisation of the Calendars via iCloud. This involved deleting the Calendar on the iPhone. The good news - two-way synchronisation for new entries is working.
The bad news - the previous Calendar entries have not returned to the iPhone. If they are not re-instated overnight, I will revert to a synchronisation of the Calendars via iTunes - and hope that I can turn on iCloud synchronisation again after that.
Then I will have to try it all again for the iPad!