I searched my fork of the driver for serverStatus, there's no results, so currently, I don't think this command is supported.
There's no associated jira (with serverStatus, at least) that i can find
Adding this functionality would be fairly trivial I would think
Edit
I wrote on the mongodb driver google group, and got this reply from Craig at MongoDB inc.
You can simply run:
MongoDatabase adminDb = ...;
adminDb.RunCommand("serverStatus");
I believe this needs to be run on the admin database.