I found An SNMP Library for .NET Framework and decided to give it a try. I made a Visual C# SQL CLR Database Project using Visual Studio 2010 beta, added the SNMP library, and created a file named sp_getInterfaces. The result was a stored procedure (within SQL Server!) that is called with the IP address and public string that returns various details about the attached interfaces.
The zipped folder includes the library and the sp_getInterfaces.cs file. My code is sloppy, but hopefully this might be enough to give you some ideas as to how you could use it to extend the functionality you get from SolarWinds.