same problem here with theme-my-login after installing SSI. The SSI logon button does appear (in my case, yahoo) but redirect does not work properly. Seems to me “redirect_to” was not being read properly.
After deactivated theme-my-login, it works slightly better. SSI Login will redirect users to the wp home page. However, it did not redirect user to the page where login was requested.
Is there anyway I can redirect users back to the page where the login link/button was clicked?