Daniel published the first article in a series about using the SharpDevelop core to build your applications. Those of you tracking the progress of SharpDevelop through the years might be wondering "Aren't there restrictions because SharpDevelop is released under the GPL?" Well, version 1.x is GPL-licensed. But for version 2.0, we changed the license to LGPL. Thus, you can use all of the SharpDevelop2 assemblies in your applications regardless of license.
Aside from the articles, there are videos showing how to write addins for SharpDevelop2. This will get you started with plugging in functionality with SharpDevelop2 via addins (again, your choice of license now!). Be sure to always get the latest bits either via our source control server, or if you prefer from our build server.
Please note that SharpDevelop2 requires .NET Framework 2.0, and, the usual disclaimer, that it is a work in progress. This, however, does not apply to the core - it has been in development for four years+, and as such is very stable and proven. After all, it is the basis for a 300 kLOC C# application!