Before anyone jumps all over me and screams "dont fly if you cant land" stuff
Some of us loves to tinker and challenge ourself and the technology out there, this does NOT mean that we don't enjoy a good (manual) flight with our planes, the one does not exclude the other!!
Some years ago there were no ECU's for our turbines, you would have to control the pump with the throttle (carefully). Now we all use ECU's and don't even think about that as strange.
Also when gyros where getting popular, a lot of the "high end pilots" were negative, "if you can control you plane, dont fly". Now they also use gyros... and so on....

Its complicated to make an autoland system, and more importantly, to get it to work safely.
I have a system with LIDAR (a laser looks down and measures precise height) so the height info is not too difficult (it also corrects for roll/pitch using a IMU). Its the "hit the runway at the center" that is difficult. GPS is not going to do it (easily), some other means is needed.

The most difficult part of the landing (manually) is for many keeping "just the right speed", not too fast and not too slow.
At least with that you can get some help: http://www.rcuniverse.com/forum/12561570-post333.html
The single most important telemetry device (in my opinion) is a speed sensor. Getting the airspeed while landing is very nice!