Copying files is an excellent issue: at some point I suggested either on the PowerShell blog or their feedback site that PowerShell should have the ability to copy files via remoting (essentially what you mention, you can remote into a box via powershell and need to copy a file from your local machine onto the remote box).

The response I got from someone at MS was quite telling, it went something like "please tell me more why you would ever want to do this, when we have existing folder sharing technology in windows". I gave up, if they seriously don't understand why that is NOT the answer to situation, gee...