Probably 60Hz. That's the main reason that 2048x1152 is about the limit of single-channel DVI and all the 2560x1600 LCDs require dual-link DVI -- there's just not enough bandwidth to keep the refresh rate up above that.
Meh. For people who need the most accurate color rendering, sure, but for CAD or just occasional graphics work, fluorescent tube backlights are fine.
Apple wants $1800 for their 30" display, and while it's pretty darned impressive, I'd sooner cough up a "mere" $1250 for HP's version:
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. I've seen them at Costco, and they're quite impressive too.
---Joel