One of the coolest feature of Windows Live Writer (the new Microsoft's tool for blogging) is that it's easy to extend and in the near future we'll see surely lots of plugins to add.
Syntax highlighting for example is one of the features that could be interesting to have on Windows Live Writer, and fortunately there's someone that has just work on this... 
Christoph De Baene has released the first version of his plugin called SyntaxColor4Writer, that enables you to embed syntax highlighting in your blog posts via Windows Live Writer.
The plugin installation it's only a simple unpacking of the package into the plugins folder of Windows Live Writer (default: C:\Program Files\Windows Live Writer\Plugins), but it requires .NET 2.0.