Deep linking (i.e. focusing a given channel and passing parameters to the channel) do not work for the guest user (it does for authenticated users).
Class GuestUserPreferencesManager has to be patch as written at http://www.ja-sig.org/wiki/display/UPC/External+Links+to+Channels+and+tabs
The attached patch is used in production by the French universities (the patch was applied to the ESUP-Portail uPortal distribution).
PA