ergophobe - 4:50 pm on Mar 9, 2011 (gmt 0)

I don't think accessibility demands warning the user, nor does warning the user imply accessibility.

I think the key is that the link is a real link, and the Javascript is external and uses the DOM to trap the link and make it a popup. Anyone with accessibility issues around popup will then be able to disable the popups and have all popups go straight to a new, standard page.