Hi Sergey / Valdimir,
I created an SSO plugin for Wordpress and put it on GitHub: https://github.com/jrchamp/userecho_sso
Please let me know which GPL2 compatible license (required by Wordpress) you want me to license it under (3 clause BSD, FreeBSD, GPL2).
Also, if there are any changes you would like made, please let me know or submit a pull request on GitHub.
Have You already filed a request to add plug-in to Wordpress Plugin catalog?
UserEcho > Settings > Project > Widgets