Today it was announced that there was a way to exploit an issue with ASP.NET and the way it returns errors. There is no patch currently, but I am sure something will come out shortly. In short the workaround to the issue is to have a customerror page...
.NET University http://www.dotnet-u.com/ is the event series that gives you a practical overview of the latest .NET technologies that is not only great to learn from, but also freely available for you to share and present to your peers. The first course...
http://devcow.com/files/9/hands_on_labs_hol/entry1... I have uploaded a Hands on Lab (HOL) on how to create a master page. This is the same format used for SharePoint 1,2,3! . I will try to put other Hands on Labs up later and these will probably be added...