Clayton Cramer makes a very pertinent point on the topic of the shared Obama-Ayers address-
In my experience, when an office has as its address an entire floor, not a suite number, it usually indicates that you have the entire floor. When multiple organizations share the same address, including an entire floor, let's just say that it is implausible that these organizations didn't have substantial overlap in staff and personnel. Imagine if the Chicago Annenberg Challenge, the Small Schools Workshop, and ten or fifteen other organizations had no connection to each other except that they all had offices on the 3rd floor--with no suite numbers to differentiate them. Would you find that likely? No, I didn't think so.
Now, you might think that the press would smell a story here and think to track down people who worked there at the time. Perhaps even go so far as to ask them if there were two separate offices or if the two groups simply shared the floor. Well, you would think that if the press weren't "just the public relations machine of the Democratic Party".