Running the powershell command
get-mailbox -database "MailboxDB" | export-mailbox -Subjectkeywords "Oracle" -TargetMailbox "rrequest" -TargetFolder "Test Query"
In my Inbox I have an Email with Oracle in the subject line. I have created an Exchange 2007 mailbox user called rrequest and when I execute the command it does indeed show at the command line messages have been found. When I open the user rrequest I see the Folder Test Query has been created and it contains my personal Inbox as well as all of my subfolders, but there are no messages in any folder and I have one in my personal account with Oracle in the subject line. The command executes and shows no errors.
Exchange 2007 SP2