I've seen a registry modification that lets you move the taskbar to different parts of screen but with my multi-monitor setup I need to move 1 taskbar to the top and leave the others at the bottom. Having a taskbar run across the centre of my desktop is very inconvenient. I've attached a screen shot so you can see what I see across all 4 monitors.
While we are at it, why not open it up further and allow people to toggle the taskbar on and off for individual screens? I'm sure that would be helpful for some people and shouldn't take a lot of time to code.