I've been using the dualhead2go for about 4 months now. I hang it off my lappy and run trip heads and frankly, I can't live without it. Takes a little mucking to get it working right with Linux but it's well worth it.
One note, I've attempted to get this working under FC5 with Xorg.7.0 and no luck. The accelerated ATI drivers aren't working well with it either, but the radeon drivers with Xorg.6.8 work great.
To anyone with spare monitors, I highly recommend it.