I finally nailed down the last bit of the wierd issue that I had with the custom Subversion post-commit hook that I wrote using C#. The cofiguration file was being read correctly in development, but that part of the code was failing on the Subversion server's hook directory. Here's actual exception from the Application Event Log:

Event Type:    Error
Event Source:    .NET Runtime 2.0 Error Reporting
Event Category:    None
Event ID:    5000
Date:        4/27/2008
Time:        12:06:29 AM
User:        N/A
Computer:    VULCAN
Description:
EventType clr20r3, P1 post-commit.exe, P2 1.0.0.0, P3 481409ae, P4 mscorlib, P5 2.0.0.0, P6 471ebc5b, P7 3404, P8 d8, P9 system.io.filenotfoundexception, P10 NIL.

I ended up removing all the code that used the System.Configuration namespace for native .NET 2.0 reading stuff, and using Nini instead.

This is now working correctly.