I am performing an Exchange 2007 transition for a global company which routes outbound internet email locally within each 2003 Admin group. The SMTP connector scopes are set to "Routing Group", not "Entire Organization". So, when I installed my first Exchange 2007 server and first SMTP "Send Connector" via the GUI console, all outbound internet email, in the entire organization, started going through it. Well, after much trial and error I figured out that by using the PowerShell to create the SMTP "Send Connector" (New-SendConnector) I could specify the ConnectorScope as "Local" which fixed my problem. The GUI does not give the option for ConnectorScope nor does it display it.
Hope this helps someone in the future cause I couldn't find anything on this at all.