Yes, but Opera basically say that there are using a MITM approach:
> To be able to do this translation, the Opera Mini server needs to have access to the unencrypted version of the webpage. Therefore no end-to-end encryption between the client and the remote web server is possible. If you need full end-to-end encryption, you should use a full web browser such as Opera Mobile.
> To be able to do this translation, the Opera Mini server needs to have access to the unencrypted version of the webpage. Therefore no end-to-end encryption between the client and the remote web server is possible. If you need full end-to-end encryption, you should use a full web browser such as Opera Mobile.
http://www.opera.com/mobile/help/faq/#security