Well, Microsoft have started adding a lot of bonuses to being gold, like 1 vs 100, the facebook/lastfm/twitter apps along with weekly discounts to games. Other than that, the actual game playing is mostly P2P on both systems so there's not much difference in the actual "service".
One thing I will add is that the 360's online features are hugely superior to the PS3.
One thing I will add is that the 360's online features are hugely superior to the PS3.