You know, emailing you your password (while still a fairly questionable security practice) after registration doesn't necessarily mean that they're storing it in plaintext. They could still have the plaintext password in memory during the registration process, including the initial email.

Same deal with a newly generated password as a result of a forgotten password link, though sites should force the user to change that on first login with the temporary generated password.

Emailing you your existing password "out of the blue", of course, is just irresponsible and unprofessional.