OK there is a Folder icon with an arrow and a trash can icon.
The folder icon allows you to chooses a file within your mail account to put the message in.
If you are using gmail IMAP and haven't changed the default the trash icon will just archive the message.
With Gmail the message will 1. be in the folder selected or 2. in the All Mail folder. To access the mail folders click on the Account name on the first page of Mail ~ landscape is the easiest..
The mail will still be in your main mail account either on your computer or webmail if used.
I found the emails in the accounts list and on the gmail website -- all except the "all mail" folder show up on the iPad. Shouldn't the "all mail" folder show up as well?
My fingers tend to drift and hit those "move" icons by accident. I wish there was a "confirm" pop up, or maybe we should have to select a "move" menu to activate it.