Lets say I can throw a satellite into orbit (I've got a good arm). I'm amateur radio qualified so can I just set it up to transmit on an amateur band and start having fun? Is there anyone I have to register with? Or am I good to go with my own license? Do I need to contact the FCC or something like that?
As far as I can tell, the IARU attempts to regulate which amateur satellites use which amateur bands to transmit, who in turn coordinates transmission with the ITU. Most countries have signed treaties with the ITU (a UN special agency) to not intentionally cause interference, etc. It looks like there are 370 cubesats currently registered with the IARU.
If you plan on transmitting to the satellite, you will also need an amateur radio license (from the ARRL if in the US), the version will depend on the frequency band operated in.