Wouter

Most likely you will know that SharePoint supports two types of pages; site pages and application pages. There are quite a few differences between the two, especially in SharePoint 2007. A site page can be customized on a per-page basis, application pages are static. Site pages are branded, application pages typically are not since they use their own master page, just to name the two most eye catching gaps.

There is however, a less mentioned difference that has a big impact on how you package and deploy your SharePoint customization. Site pages are compiled against the Microsoft.SharePoint assembly and application pages have their base class LayoutsPageBase in the Microsoft.SharePoint.Administration assembly. And here-in lies the rub so to speak. While the Microsoft.SharePoint assembly is in the GAC, the administration assembly is not.

So, when you create some code that can be executed as a part of a scripted environment, be sure to separate out your code that is administration related and that which is content related. By putting your code in two separate assemblies, you can be sure that your content assemblies do not reference the Microsoft.SharePoint.Administration assembly. Since the SharePoint administration assembly is stored in the CONFIG\BIN folder, the .NET runtime cannot find it when for instance loading feature receivers or safe controls.

So, separate your administration from your content!

Hope it helps!