designer2k2 --
The Arduino is doing something that until now has required a full computer.
This task has two components. To use a communication satellite, first you need to know when it is visible to your station and in what direction. This 'tracking' requires a computer/microcontroller to compute the position of the satellite, each second or so and then compare this to where you are on earth.
Once you know the satellite is visible, you have another problem, and that is that the frequencies on which it is receiving and transmitting do not stay still; they shift like the whistle of a train passing by. Because the frequency of the satellite's radio link is much higher than the train whistle, and the satellite much faster, this 'doppler' shift is in the 10's of kHz for some satellites.
So in this video the Arduino is tracking the satellite and changing the receiving and transmitting frequencies of the radio so that it can talk to a satellite. In the second half of the video, it is tuning in a single tone morse code signal, which, despite the doppler shift, is staying within a 100Hz range, a very good result for any tracking program, much less one that runs on $4 silicon.
The hardware side of this is going to sit on a 1" x 2.5" board that snaps onto an Arduino Mini Pro. With the 328's EEPROM, the qrpTracker can keep track of about 10 satellites, tuning the radio as each appears.