In a weird, but strangely understandable, turn of events. Bing Webmaster Tools now let you log in using your Google or Facebook account.
The goal is to make life a lot easier for webmasters (so you don’t have to worry about another username and password).
This is what the new login screen looks like
The main thing to note here (according to Microsoft) is:
means that the messages Webmaster Tools may occasionally send you about your managed properties will be sent to the email account associated with the webmaster tools account you are logged in with. The most recent messages will still be available in your Webmaster Tools Message Center.
An interesting move and I must say, not unwelcome.
You can access Bing Webmaster Tools here bing.com/toolbox/webmaster