SqueakD
the other one should be OpenLabs Neko,Windows based monster keyboard(without DSPs??!!).Be shure that after Yamaha aquiring VST rights the next 'big thing' form them should be a DSP/'Open' system.
One (big?) difference is that OASYS does not seem to allow to intergrade third party software audio generators like the rest 'Open' systems.
For the history the Wersi Pegasus was the first (again!) keyboard to use touch screen and built in hard disk -all these in 1993, and the Korg i30 looks very much like an 'improved' version of the Pegasus.And the Wersi OAS is out since 1999 (I got mine in 2001)-Icarus was launched in last year's Winter NAMM.