The process is quite simple, just touch two NFC enabled devices together and tap the screen. It then sends all the information for what you are beaming to the other device nearly instantly. In the video they show how simple it is to share web[ages and Google maps. The beam service will work with people cards, contacts, photos, YouTube and Applications/Games. Touch the devices together while you have your favorite game opened and the other device will be directed to the Android market to install it.
To give the service and the capabilities a little push in the right direction, they are releasing the API’s for the beam service so developers can start creating even more amazing and unique applications. Should prove to be very a interesting technology for the devs. You can check out the Beam presentation at time marker 53:05 of the full announcement.