i think it could just be for giving feedback for wordpress - it seems like that if it takes you to their support page.
Well but that doesn't make any sense, there is already a support forum for my plugin. The "Review" link URL is this: http://wordpress.org/support/view/plugin-reviews/automatic-post-tagger So I guess that WP is preparing a new feature for reviewing plugins but there is not a word about it on the dev blog. -_- If anyone has more information please let me know.
I checked the Reviews tab again today and it does not redirect to the support forums anyone but there is a page with a form for adding reviews (how surprising).
It is a new feature that assists in reviewing and rating a plugin. Moreover, I would like to share a plugin that integrates with a WP site and help in rating and reviewing. http://wordpress.org/extend/plugins/re-vu-comment-system/