I found this information on a forum as to why it outputs at 1280 x 800 as the max resolution for single link into dual link 30" monitors instead of 1920 x 1080 like a PS3 is capable of.
Both dual-link and single-link dvi use tmds to transferee data from one device to another. Therefore the output device uses a tmds transmitter and the input device uses a tmds receiver.
-The difference between dual-link and single-link is dual-link uses 2x tmds inputs/outputs whilst single-link uses 1x tmds inputs/outputs.
-The maximum output res of single-link dvi is 1920x1200, companies can choose to use a tmds chip of a lower frequency therefore supporting a lower resolution. There in lies the secret behind the 30".
-The 30" screens use 2x tmds receivers each able to input 1280x800 - if you double that you get 2560x1600.
-Therefore when your using a device which outputs via single-link it can only access a single tmds input - which limits the output to 1280x800. To use any higher resolutions you need a dual-link output to access both tmds receivers.
-So whilst the single-link dvi output may use a tmds transmitter which is able to output a frequency to support 1920x1200 if the input device uses a tmds receiver which maxes out at a lower resolution there's nothing you can do about it.
So it looks like you'd need a tuner card to be able to upscale or run the ps3 at the right resolution.