Andrew is asking about the JetBrains C# IDE, I did some research right now, and literally all information about it is dated to 2005. There is no official response saying this, but I guess that JetBrains decided that there just isn't a point in trying to compete with Microsoft in this area. I find it very sad, since by and large I am very unhappy with VS itself, and I have been continually impressed by what JetBrains' stuff enables me to do.
I would really like to see an IDE from JetBrains for .NET. It is a big undertaking, but I have faith in their abilities to make it work. JetBrains, please give us a reasonable IDE, I am so tired of fighting VS, I want an IDE to be my friend not a foe.