For those who are still looking for a open source .net blog framework. I think this is what you're looking for. Enjoy blogging! :)
BlogEngine.NET is an open source .NET blogging project that was born out of desire for a better blog platform. A blog platform with less complexity, easy customization, and one that takes advantage of the latest .NET features.
BlogEngine.NET was designed using the current .NET framework and focused on simplicity, ease of extendibility, and innovative features. With BlogEngine.NET, we hope to create the natural blog of choice for all .NET developers world wide.