Updated 130313
VIP has a high volume of remote play using a variety of PBEM tools. VASSAL is a free cross-platform tool enabling both stepped review PBEM and real time server play. Windows-specific tools include: Aid de Camp II, Cyberboard, and the Wargame Processor.
Most organized play is found on John Pack's VITP PBEM Ladder and various Boardgame Player Association PBEM tournaments. This high volume of game play has served to standardize PBEM game play with rule interpretations that are shared with the big three Face to Face tournaments and recorded by Avalon Hill's officially designated Q&C keeper, Glenn Petroski.
http://www.gameaholics.com/vitp_tournament.htm