I thought that would be the likely result, I'll just wait until the newer crop of passive displays come out. Eyefinity can work with the interlaced displays because the iz3d and tridef middleware see the eyefinity display as one large surface, and render the stereo output interlaced to that. Since the monitors have the same vertical resolution and interlacing pattern for the 3d polarisation it should "just work". Obviously performance will be poor without a serious graphics card or a rather old game, but by the time there are new monitors out the latest crop of AMD cards should cope.
There's a youtube video http://www.youtube.com/watch?v=Bm0MyJmDboo&list=UUYcrZ8is9RbAB8jZkqH9WYw&index=23&feature=plcp
which shows it kindof working, but I plan to test it with my current setup before I fork out (connect 2 connections to the zalman and one to another monitor to make it go into eyefinity, and check the centre and outer images on the zalman look right).
I'll try this later in the week and report back if it does properly work.