target blank is not good for a11y, if used it must be explicitly stated in the link text that the link will open up in a new window. for more info read the following
- http://www.w3.org/TR/WCAG20-TECHS/G200  
- http://www.webcredible.co.uk/user-friendly-resources/web-usability/new-browser-windows.shtml
- http://css-tricks.com/use-target_blank/