My PS3 Fat 60GB was a shoddy performer on wireless, no matter what combo of tweaks I did on my router and unit itself. One thing that helped quite a bit was hard coding my DNS servers, but not tremendously and I honestly chalk it up to voodoo, but the Fat model always underperformed via wireless for me.
My PS3 Slim on the other hand, has been an excellent wireless performer out of the box with zero tweaks or adjustments on either end (I didn't even reserve it an IP and disabled all the rules I set up for the old unit). This includes a lot of gaming, downloading demos and streaming NetFlix. No idea what exactly changed in the hardware, unit is in the exact same location, etc... but my slim performs like a champ via wireless.
The only true currency in this bankrupt world is what we share with someone else when we're uncool. -Lester Bangs