It's supposed to work in Linux. They say with a little editing and loading a standard module or two the device is recognized as a serial modem and you can dial with a regular ppp dialer. The Verizon software is unnecessary.
Use on the Zaurus may be less than optimal, however, because the USB720 uses a good bit of juice grabbing weak signals and some laptops can't keep it powered with a single USB port. So the device reportedly comes with a Y-cable so you can plug it into two ports and sufficient power. That's one more port than any Zaurus has. Perhaps a battery powered USB hub could do the trick, but quick access and convenience will suffer.
Check these sites and search for USB720 for details. There is probably more information available for some of the earlier USB devices which may be applicable to the USB720. Howard ForumsEvdo-CoverageEvdoInfo
Any news of actual experience -- particularly whether it works well enough to be worth it -- would be of interest to me as well.
edit: oops, I see you were asking about the Sprint rather than the Verizon version, but the forums seem to think they work the same. I believe it's the same or similar hardware underneath.