I developed a test web part and everything worked well. Now I try to deploy another webpart without using GAC (several websites, including Microsoft's, say that the web part dll must either be in /bin folder or in the GAC).

Now, when I copy the dll of the webpart into the /bin folder, it is not shown in the available webparts in SharePoint 2010.

A restart of the server didnt work, nor adding it to the web.config.

How can the webpart be registered to SharePoint?