I get an error saying that it cannot log into remote server, and that my password/username are incorrect - although I have re-entered and they are correct.It appears that Blogger may have created a backdoor, to allow LiveWriter client access - which requires a new Google setting.
One forum post suggests a backdoor setting, in Google Security, which appears to enable LiveWriter to login to Blogger.
IT'S WORKING AGAIN!!! With a caveat - you'll get an error message about not being able to log in. After you do, check the Gmail account associated with your Blogger. Open the link to control your access security settings (https://www.google.com/settings/security/lesssecureapps) and allow "Access for less secure apps." Then click the back arrow. Quit LW, then open & try again.
Click here for the "LessSecureApps" wizard, in Google Security.
The setting provided appears to be global. If you have other apps which use ClientLogin, this may or may not provide a complete and safe solution.
Some apps and devices use less secure sign-in technology, which makes your account more vulnerable. You can turn off access for these apps, which we recommend, or turn on access if you want to use them despite the risks. Learn more
It's your option, to allow all applications which use Google to authenticate, to use the less secure "ClientLogin" process.
If you are using Google 2-Step Verification, you can't use this new option.
Some third party offline editors may still need to be upgraded - as it does not appear that the "Less Secure Apps" option is a built in feature in OAuth 1.0. Your experience, and feedback, is welcome.
(Update 2015/12/16): Windows Live Writer has been replaced by Open Live Writer, an Open Source project. OLW will only work with OAuth 2.0, and is available for download.