From scavaging the around the web, I pieced together the follow steps to setup TortiseSVN's revision number (aka subwcrev) and timestamp as part of the assembly version.

1. Copy the existing Properties\AssemblyInfo.cs file to a file named AssemblyInfo.template
2. Edit the file, changing to the following:

   [assembly: AssemblyVersion("1.0.0.$WCREV$")]
   [assembly: AssemblyFileVersion("1.0.0.$WCREV$")]

3. Edit the Project properties, adding the following Pre-Build events:

   cd "$(ProjectDir)"
   SubWCRev . "Properties\AssemblyInfo.template" "Properties\AssemblyInfo.cs"

4. Build your code, and display the assembly version info with the following snippet:

   this.Text += "- " + Assembly.GetExecutingAssembly().GetName().Version.ToString();