And I am also still having the exact same problem. I have made a new (complex) password, and that password works fine via the web interface and the password allows me to receive mail via IMAP on all devices. I can receive mail on Snow Leopard, but I cannot send via SMTP, regardless of whether I use smtp.me.com, smtp.mail.me.com, or smpt.icloud.com, using SSL, etc., etc. I've tried every combination possible. If I try to create a new mail account for a me.com account, it fails. All of this had been working fine for years - no changes - and something just changed, but not on my end. Under the System Settings on 10.6.8, if I click on MobleMe (yup, it's still there), I continue to get the following, even after signing out/in/out/in:
Something is screwed up at Apple, and this is getting old.
--Rich