Not sure that dilution is occuring as the direct result of options being exercised, as those shares would have already been accounted for when looking at the "fully diluted" stats for the company. Also, giving the company the right to issue more options is not dilutive, but does portend dilution when those options are awarded.

Of course, many think that shares are being sold in order to fund the exercise of existing options; I would think that some of that has been going on. That's not dilution, but it certainly puts downward pressure on the share price.