Today I received this fine, fine email from Writely.
In a few days, we will update your Writely account to use your email@example.com Google Account registration settings.
This means you’ll need to use your Google Account password when signing in, not your Writely password (if they’re different).
If you’ve forgotten your Google Account password, just go to https://www.google.com/accounts/ForgotPasswd
Google Writely Team