We often hear the term "[product] killer" used in reference to some new device recently released or to be released, but are often dissapointed, so I'm going to avoid using that term here. That aside, Sony is very confident that their challenge to Microsoft's Xbox Live service will be more than just an equal. Apparently they are planning a service that not only will offer what Live offers, but many other interesting features such as the possibility for extremely large games (think >32 players) and seamless interaction.
A decent online service is lacking for PS2 and possibly PSP, so even on a lesser scale it would still be welcomed. I'm looking forward to seeing what Sony has in store, though I doubt Xbox Live is in any trouble.