Most mobile phones today support bluetooth and can be used as a bluetooth remote. Given that the bluetooth runs without problems this can easily be activated: just identify the hardware address of your mobile phone and connect to it:
$ hcitool scan Scanning ... 00:2E:15:D3:59:21 MyPhone $ hidd --connect 00:2E:15:D3:59:21
Unfortunately this has to be done as root (at least here on Fedora 8), but after these lines have been entered the phone should offer the option to accept the connection and probably also asks which kind of service (desktop control, presentation control, media player control, etc.) it should deliver.