Microsoft will also be hosting several Game with Fame events during the five-day promotion of the delayed expansion, including allowing players to play against the developers at Rockstar who made the game. Game with Fame events are a regular occurrence on Xbox Live, so scheduling them during the promotion should give silver account holders a taste of what the Xbox Live community has to offer.
I'm sure Microsoft feels a lot of pressure to get a return on the $50 million investment put into Xbox 360 exclusive content, and this promotion might help get there. The idea is that people who don't already have a gold subscription to Xbox Live will get hooked to the online play and shell out the $50 yearly fee. Will it work? A handful of people will be converted by the promotion, but probably not $50 million worth of subscriptions.