Here is an interesting one on the latest public build.

I get the message "Unable to Move Message - The message could not be moved to the mailbox Trash." on my iphone and iPad.

The other day I was in my groupwise mailbox and the position of my Trash box had been moved up to the top from somewhere done at the bottom. So I moved it back down to the bottom, not sure of the original exact position. After that I was no longer able to throw items away on either device (ipad or iphone). I can move them manually to the Trash box as a move but not as a delete from the device.