I'm surprised none have mentioned it, but the Xilinx ML501 has finally been released officially, even though it's not available online yet.
Press release:
It looks to be a very compelling kit. Unfortunately for me, the XC5VLX50 isn't supported by the WebPACK and unlike with the original ML401 release, software is _not_ included so unless you can afford the full ISE package also, don't bother.
Tommy