I'm sure this feature wont be easy, This would be very usefull, but there should be some things in place to prevent it being annoying.
wait for the player to have fully loaded all the data,(models,textures,xml's, ect,ect).
And a dropback to menu "option" _WITH_ the data saved. No reason to "re"load the same data as long as you are trying to connect to the same game.
So.
1.Drop-out
2.AI-takes control
3.Server acknowledges the client trying to reconnect(some sort of check here to be sure it's the same player,some sort of disconnect password*1). When the game disconnects show a disconnect password/id in the upper right side of the screen*3 until a new game is started.
4. User goes to the internet games lobby. Here he can join new games or join the existing game. if he joins a new game and it start's. he will lose the ability to join the old game.
5.If he try to join a game in progress the game asks for the game-id(the server handling the network connections i presume? ).
6. Server accepts or rejects connection depending on game.
7.Game starts loading for player.
8.All data is loaded game client
9. Game client sends a flag/signal/packet? (*2), to let the the server know im ready for game syncrynosations now.
10. Game syncronises perhaps a pause is in order for the game to be in a "perfect" state of sync before starting again?.
*1 in case you are permantly disconnected and you want a friend to connect
*2(not sure what a coder term would be for this).
*3 Image of said text
http://img29.imageshack.us/img29/2166/disconnectid.jpgPart 2. -- The simple connection --
1.Client drops, when a client becomes aware it is dropped it either drops to main screen with only 2 buttons "leave game" and "reconnect". OR still ingame a screen appears "you have been disconnected, reconnect?" yes/no.