Wow, I have never seen so much rampant unfounded "facts" being thrown around a forum. Let me elaborate:
"They also claimed that memorysticks from PS1 would work on PS2, which didn't. But all is forgiven by backwards compatibility. Go Sony!"
I assume you mean memory cards, and yes they do work on PS2. They just only work with PS1 games. No shit. They are way smaller. That's pretty obvious.
"yay backwards compatibility. That makes it 100% certain that your new games are being slowed down or held back by the old games."
The backward compatability is simply an addon software emulation and will not make one damn difference when you are playing a PS3 games, it will only be loaded when an older game is played.
"PS1 games look dodgy on the PS2 if you use the S-Video lead to get better graphics with your PS-2 games."
The PS2 has an option to which actually attempts to make PS1 games run better, but you can turn this off and things should be exactly the same as a PS1. It's called "Faster Loading and Smoother textures".
"I sure as hell hope PS3 has component video ports for HDTV's. That would rock. "
I'm sure it will but it may be in the form of a separate cable just like there is with the component cable on the PS2.
Hope that helps.