Let's try to clear a few things up:
1) What we're talking about here is hooking up some PS3's to each other, using network cables, without connecting to the Internet. If you're still confused about this, here's an analogy which uses phones -- ignore the wireless vs. wired issue and focus on the connectivity portion of this analogy: Think of it as using walkie-talkies instead of phones. The phones require the phone company's infrastructure -- the walkie-talkies do not.
By the way, this is how ALL networking games used to work, when they first came out. I remember playing Doom this way against fellow co-workers after hours on our local network, until the Powers That Be told us we were making too much noise.
2) In order to hook these PS3s to each other, you can't just run a network cable from one PS3 to another. Instead, connect them all (wired or wirelessly) into the same router or switch. This is how they will talk to each other.
3) Using this setup, the games don't connect to a central server. So this only works with games that support this type of "ad-hoc" play. I doubt it would work for "High Stakes on the Vegas Strip: Poker Edition", for instance. I don't know what games support this and what ones do not.
PS: I sure hope it works, because I've never actually done it.
But I'm a computer geek, so I understand the concepts. gd&r