I remember that some time ago I had the need to interact with a library written in .NET from MS SQL 2000. Creating a COM+ object using managed code was the first thing that came to my mind (I had done it before using C++). I googled it for a little bit but couldn't find the right way to get this done and since I was really in a hurry ended up creating a simple console application that was called using xp_cmdshell.

Today I had the time to revisit this issue and this time in less than 1 minute the right article came on top of my search results: Microsoft Enterprise Services allows you to create Microsoft COM+ applications using the .NET Framework.

This is the article that explains this process in details:
http://support.microsoft.com/kb/306296

How to invoke COM applications from SQL?
http://www.sqlservercentral.com/columnists/dasanka/callingcomfromtsql.asp