We have been using it in SLES 10 and mono 1.9 for quite a while now. Only the ASP.net part and not the Silverlight stuff... not yet.
There is a small problem with 64bit SLES 10 SP that we are trying to solve... Have not tried it on the Mono 2.0 preview yet.
see my posts to VWG about the 64bit problem here
VWG 6.1 on SLES 64 bit and Mono 1.9.1 give Invalid IL codeMaybe you have a solution for it..
Maybe you can post your WebGUI Howto here on the mono forum? (If thats allowed)