Let's not get too excited
A lot of people (e.g. Sean Hannity in the five minutes of his show I heard in the car today) are pointing to the tape said to be bin Laden as evidence of a link between Iraq and al Qaeda (here is the story).
However, I don't see anymore of a link between the two than that referred to by Powell: it indicates a "nexus" between rogue states and terrorist groups. It doesn't indicate that al Qaeda and Iraq have been actively cooperating for years or anything. I think some people are really searching for a link between 9/11 and Iraq, and they are too-quickly pointing to this tape as proof, when there is nothing of the sort in it.