Great idea, a External display via the firewire 400 port on my computer!
Lets do the math
(bare in mind that this done assuming we want 24 bit displays at 60hz)
Firewire = 400 Mbits
SXGA = 1 310 720 pixels
Each pixel is 24 bits / 3 bytes
therefore 3 932 160bytes (3.75 Mb) required to refresh the display each cycle.
average display is refreshed 60 times (60Hz) therefore 60 * 3.75
Total required thoughput of 225 Mb/s
Firewire total thoughout = 50 Mb/s
Thats why it's a express card job
Another reason why Having no express card port on this macbook is starting to suck. a 13" macbook pro would have been really nice right about now.
Another bright idea, external display via gigabit ethernet, nope only 125 MBit/s. Looks like my dream of a dual headed macbook is kinda dead. It's a mathmatical impossiblity :(
Since i was in this frame of mind i wondered, what the thoughput of a DVI connector might be
6.5 Mb per cycle
2560 * 1600
11.7 Mb per cycle
A nice indication there of how much pixel pushing a graphics card really does in order to devliever a rich high resolution experience. Still no reason for crappy open source support, but it at least makes it clear why graphics cards have to be so damn powerful.