I use Gmail IMAP with Outlook 2007.
I created new folders under "inbox" in Outlook 2007 and set a rule for some of the incoming messages: when an email message arrives from a particular email address, the message will go directly to one of these subfolders.
It works great in Outlook but the messages are actually totally erased from the Gmail servers (I think; they are not in the Inbox when I check the Gmail web interface).
When using IMAP normally Gmail saves a copy in their servers too. Only when using subfolders and this rule it doesn't work.