When I purchased my P5, the dealership offered an alarm/remote start package which I went for. I have one remote, and the alarm now controls the keyless entry, as well as the starter.
And MacDaddy is 100% correct - I don't know what kind of car your buddy had, but nearly ALL automatic tranny cars are designed to only be started (with the key) in Park or Neutral. If his car was able to be started in gear, something was wrong with his car.
My remote start works like this: The car is in park, you activate the remote starter with the key fob, the car starts about 2 seconds after. Now, because of the factory brake lockout on the P5, you cannot shift out of Park without pushing the brake pedal. However, if the brake is pressed without the key in the ignition, the car shuts off. This makes it impossible for someone to get in your already-running car and drive off without the keys. And there's no way for the car to just "slip" into gear.
I love the remote start - thought it would be a gimicky thing I used to impress my buddies, but I seriously use it all the time now. Not so much to warm or cool the interior (although that is nice), but to warm the engine, so that I can just get in and drive, without feeling as though I'm driving my car completely cold.
I would think that you could get a remote start for a manual tranny (though I don't know who will install it for you). This is really dangerous, though (and illegal for a shop to install, I believe) - all it takes is parking the car in gear without the parking brake and that's the end of your car if you remote start it. But I would think that some sort of interlock could be set up, so that unless the car is in neutral and the parking brake is set, it won't start, Sounds like a bit of work, though.