(A complete speculation, admittedly, is the connection with the first dead guy's occupation: a photographer for the weekly tabloid "The Sun." Speculations that he was photographing the WTC pilots and their small plane for a "scoop" on bioterrorism are unsubstantiated.)
Additional information from various reports: the first victim, Stevens, lived about a mile from the airport where the hijackers practiced. The Star office building is a few miles away. Stevens' keyboard at his office was found contaminated with Anthrax. The second victim was not infected internally with Anthrax but spores were found in his nose. One of the purposes of the nose is to filter junk out before it gets to the lungs. If the Anthrax spores are the wrong size they will get trapped like this. Part of the art of preparing Anthrax weapons is getting the particle sizes exactly right. Hypothesis one: the Star reporters were trying to get a "scoop" on bioterrorism. Impossible! How would they know where to find bioterrorists? Did Mohammed Atta and associates go around calling up tabloids and offering them a "scoop"? This is inconsistent with the utter professionalism and secrecy with with the operation was conducted. Hypothesis two: Stevens was infected via aerial spraying at his home and carried the spores into the office. Unlikely but possible. It would be difficult to bring enough spores in just on his clothes and person as to contaminate the office and get spores into the nose of his co-worker. And why were more people near Stevens' home not affected? Possibly the spray was extremely ineffective and only Stevens was unlucky enough to get a fatal dose. Hypothesis three: the Star office building was a test for distribution of Anthrax spores via internal air circulation. Unlikely but possible. One would expect to see more internal contamination in the building than just Stevens' keyboard, and more Star employees affected than two. Again it is possible that the delivery was inefficient. It may be that more contamination was found which has not yet been reported. Hypothesis four: Stevens was infected through natural environmental exposure away from work and brought spores into the office. Highly unlikely, given the rarity of Anthrax exposure and the difficulty of bringing in enough spores to infect someone else. Hypothesis five: Stevens was infected through natural environmental exposure in the office. Extremely unlikely: Anthrax is found on animal products (previous industrial cases have involved exposure to such things as goat hides) and a photography editor would not be handling such materials. The most likely possibilities appear to be numbers two and three, that this was either a test run or a botched attempt at infecting the population. The experts have been claiming for weeks that handling these bioagents isn't as trivial as fearmongers would suggest. It seems probable that such factors are at work here.