zohararad/bootstrap — pull request #1 by dorongutman (2012-12-28 11:44:58+00:00)
Title: Reverted two wrongfully rtl'ed valued

Looking at the original purpose of the pull-left class inside a media item, you can see that the margin is to the right, so there will be some space between the image and the text.
Same for pull-right with a margin to the left.

See the way it works in http://twitter.github.com/bootstrap/components.html#media - inspect the image.