The Guardian's Game Blog points out that the PS3's latest firmware has a few online features that is making Xbox LIVE's online advantage tenuous.
Two such features are "XMB" and "Trophies." XMB is Sony's cross media bar (if you own a Bravia TV or PSP, you'll be familiar with this) which in the case of online PS3 means that you can message friends, issue invites, etc., in-game. Previously, you would have to exit out of the game to do this.
Trophies are essentially Xbox Live achievements.
The blog entry finishes...
Of course, Live remains more tightly integrated and is likely to remain the better service even with these PS3 updates. But the gap is closing and you have to wonder how long Microsoft can go on charging for access to Live when many of its features are free on PS3.