More ability to customize and work on multiple monitors.
For example, right now I have liquid dream running on three monitors. The way it works now, the effects and the background image are the same on all three (clones), which isn't bad, but I'd like to be able to get a more seamless experience with something like a properly tiled background. Or let me specify a different background (or effect) on any of the different monitors, even if using the same dream.
I'd like to be able to configure it so that a different wallpaper is used on each of the screens (or, if possible, have it set up so that it will properly tile a 3 monitor wallpaper across the screens, in the same manner that the tile feature in windows does).
Even better, let the dream be configured to span the entire space defined by the multiple monitors. For example in my 3 monitor setup (3 x 1680 x 1050), let the dream be configured to present a single experience across all three monitors.
I think it would be appropriate to treat the whole workspace as a single workspace, no matter how many monitors are involved. This might not be easily possible with video dreams, but it should be doable with dynamic dreams.
I'm pretty happy with the current state of multi monitor support, it's definitely better than what we had before, but I think it would be nice if we could get more contol over *all* of the presentation for a multi monitor setup.