<p>Anybody have a script or alias to find untracked (really: unadded) files in a Perforce tree?</p>

<p>EDIT: I updated the accepted answer on this one since it looks like P4V added support for this in the January 2009 release.</p>

Ahh, one of the Perforce classics :) Yes, it really sucks that there is STILL no easy way for this built into the default commands.
The easiest way is to run a command to find all files under your clients root, and then attempt to add them to the depot. You'll end up with a changelist of all new files and existing files are ignored.
E.g dir /s /b /A-D | p4 -x - add
(use 'find . -type f -print' from a nix command line).
If you want a physical list (in the console or file) then you can pipe on the results of a diff (or add if you also want them in a changelist).
If you're running this within P4Win you can use $r to substitute the client root of the current workspace.