This is the first post I’ve done using Open Live Writer (OLW). With the release 0.5.1.2 there is support for Blogger after Google updated their API to use OAuth 2 and thus breaking the functionality in the old Windows Live Writer and the initial release of OLW. The error was: Blogger returned the following error: NotFound: Not Found.
A known issue with this release is that labels/categories can’t be set when posting to Blogger.
For some background on how Microsoft’s WLW became Open Source OLW see the Announcing Open Live Writer - An Open Source Fork of Windows Live Writer post by Hanselman.