I have a suggestion. Fake a video of his capture. Show him pleading for his life with terror on his face under the boots of US Rangers and CIA like Hussein. We certainly have the technology to fake his facial features and mannerisms.
Leak it into the YouTube world of deniablility. When the US government denies any knowledge of the video it would be perceived as just another one of those lies that they always tell. Of course there would be all kinds of conspiracy theories out there.. but it would force Bin-Laden to the surface to deny the claim. It would be one thing if it showed him killed and that would be to his advantage, but cowering in fear is an insult to his honor and a response in that culture would be required.
If for nothing else we could determine whether he is dead or alive. No response would indicate the worms had long ago finished with him.