In JMS 1.1.x, the answer is NO.
In JMS 1.2.x, the answer is YES with some limitation described in the product detail.
www.jms2win.com/download
The single sign-in only work on the same domain.
This mean that you can have slave site in a subdomain or a subdirectory.
The single sign-in require that you share the users between the website.
See the tutorial video 16 that show how to share the user and extensions.
www.jms2win.com/tutorial#jms12x-16
The extension sharing require that you are using MySQL 5.0 or higher and that you have the MySQL user privileges to share the MySQL tables.