4E has IMHO the lowest barrier to a good night of gaming. As a father of two, and a full time researcher, I have barely enough time to game as it is. Our game nights are packed now that we playing 4E. I probably won’t forget the 2nd game night using the new rules: 3 hours = 3 combat encounters and 3 ‘non-combat’ encounters = 6 things done. All the players shined both in combat and out, and everyone had an awesome time.
This is why WotC really needs to get their digital tabletop right. Combined with a game that makes it easy to pack a lot of fun in a limited amount of time, making it easy to get together with friends is a killer synergy. If they can then help cultivate better DMs and better players through the communities that develop around DDI, they can possibly inject a lot of life into the hobby.