Last week this story came to an end with the announcement of Open Live Writer, an open source fork of Windows Live Writer. Although some features are still missing, this is great news as it will give
Inside the announcement, the support for OAuth 2.0 was mentioned as to be added 'VERY SOON':
ADDING VERY SOON: Google runs the excellent Blogger blog service. We've worked with the Blogger Team within Google on this project, and they've been kind enough to keep an older authentication endpoint running for many months while we work on Open Live Writer. Soon, Google and Blogger will finally shut down this older authentication system. Blogger will use the more modern OAuth 2 and Open Live Writer will be updated to support OAuth 2. Windows Live Writer will never support this new OAuth 2 authentication system, so if you use Blogger, you'll need to use Open Live Writer.Unfortunately the Blogger guys didn't read the announcement very well I think, as they disabled the old authentication endpoint immediatelly :-( So if you try to connect to Blogger using either Windows Live Writer or Open Live Writer, you'll get a 'Not Found' exception.
I hope a fix will be available soon as typing in the online editor ain't fun!