I’m working on setting up a scale-out SSRS installation.  We’ll be shutting down the old URL soon and everyone should be off it.  I can tell who is still hitting the old URL, which leads to the old server by using this query.

We’re using the ExecutionLog2 view in the reportserver database. Much easier than joining tables together and trying to build paths to reports with a CTE.

More information on this view.
http://blogs.msdn.com/b/robertbruckner/archive/2009/01/05/executionlog2-view.aspx