Problem Solved
There's finally a fix.
http://www.macosxhints.com/article.php?story=2006110314322775
--------------------------------------------------------------------------------------
On the Mac Pros, Front Row is installed but refuses to launch. You can see it is installed, as the application file is in /System -> Library -> CoreServices, and it is even an option to install on the Restore DVD. But Command-Escape produces nothing, and double-clicking on the app just creates two entries in the Console log: Bootstrap not privileged and No Remote Present. The first message is not an issue (Front Row is not supposed to be started from a double-click), but the second gives the answer: Front Row does not launch because it checks to see if the Apple IR remote is present. So the solution is to fool the system into thinking there is an IR remote...
It can be done by a simple edit of a plist file. Credit for this goes to the InsanelyMac forum members, who posted the solution in this thread. As usual, do a complete backup before proceding, just in case something should go wrong.
Case 1: You use an Apple mouse (eg the Mighty Mouse provided with your Mac Pro).
In Finder, choose Go > Go to folder and open /System -> Library -> Extensions -> AppleHIDMouse.kext -> Contents. Select Info.plist, do a Get Info (Command-I), and change the owner to you. Open it with Apple's Property List Editor or Plist Edit Pro. Unfold Root -> IOKitPersonalities. Select M19-0a, then click on the New Child button. Change the New item key to HIDRemoteControl, select it (HIDRemoteControl) and change its class from string to boolean (value = true). Do the same with M19-0b and M19-1: new child HIDRemoteControl, boolean = true.
Save the plist file. Open its Get Info window again, and set the owner back to system. Go to /System -> Library. Delete Extensions.kextcache and Extension.mkext (these are cache files that will be rebuilt at boot). Reboot.
Case 2: You use a Logitech mouse with the Logitech Control Center installed.
In Finder, choose Go > Go to folder and open /System -> Library -> Extensions -> IOUSBFamily.kext -> Contents -> PlugIns -> IOUSBHIDDriver.kext -> Contents. Select Info.plist, do a Get Info, and change the owner to you. Open it with Apple's Property List Editor or Plist Edit Pro.
Unfold Root -> IOKitPersonalities. Select Generic Keyboard, then click on New Child button. Change the New item key to HIDRemoteControl, select it (HIDRemoteControl) and change its class from string to boolean (value = true).
Save the plist file. Open its Get Info window again, and set the owner back to system. Go to /System -> Library. Delete Extensions.kextcache and Extension.mkext (these are cache files that will be rebuilt at boot). Reboot.
Case 3: You use another mouse
First, try Case 1 and Case 2. If it still does not work, plug in an Apple mouse on USB (even if you do not use it!) and make the edits. After next boot, unplug your keyboard and mouse, and plug them back. Hit Command-Escape, and enjoy Front Row.