Some of them are.
iz3d is almost purely for gaming, and is too buggy to really be worth it in most cases.
Zalman's can run off of the Tridef drivers (and nvidia's if you have an nvidia card), which can convert 2d DVD quality files into 3d, which according to reports, actuall works rather well (I'll let you know if I end up getting the monitor), and at the moment are the cheapest and highest resolution 22" 3d setup, and iz3d and zalman glass cost about 1 15th of the nvidia glasses.
The 120Hz monitors provide an equal 3d setup on pretty much any game, but 2d/3d conversion drivers aren't as effective on these setups, especially as generally the video only has between 20-30fps, which gets halved by turning it into 3d causing massive headaches and unconvincing 3d.
