Linux flavors are increasingly supporting CLR binaries through "Mono". I've talked to several .NET developers who found porting to Mono pretty easy (and Mono apps run as-is under .NET).

For instance, Ubuntu and Debian now both come with several .NET apps as default apps (e.g. TomBoy).

And the Mono development platform (MonoDevelop) is far better supported under Mac/Linux these days than Eclipse, due to Sun's past restrictive licensing of Java.

You can find non-Windows SOS clients at http://www.sourcegear.com/sos/downloads2.html. For those clients, the binaries are a GTK based client, so you'll need to make sure you have dependencies (like glib 2.x, etc.) to use it. Also note, ALL SOS 4.2 clients can connect to the SOS 5 server.

In regards to your post, are you suggesting a change in how the SOS client works, or have you not seen the clients yet?