Unfortunately we're having some trouble with the Sourcefire Nation website, where the package is hosted. If you're having trouble, please try again in a few hours. I can say though, at this moment the site is up and you should be able to download it.
Thank you for the interest!
We're working on a permanent hosting solution, but in the meantime I have posted the current version of the app on the Cisco Support Community site. Below is the temporary location that can be used to get access to the app.
Please note this URL may disappear at any moment, but that should indicate a permanent solution being found.
Again, sorry guys.