The first line, "#include <tunables/global>" needs to go below the

"/usr/bin/dropbox {" with the other includes.

Also you can consolidate

owner @{HOME}/*/.dropbox-dist/ r,
owner @{HOME}/*/.dropbox-dist/** r,
owner @{HOME}/*/.dropbox-dist/ncrypt-0.6.4-py2.5-linux-x86_64.egg/_ncrypt.so mr,
owner @{HOME}/*/.dropbox-dist/netifaces-0.5-py2.5-linux-x86_64.egg/netifaces.so mr,

And why do you have a * in "@{HOME}/*/"

specify a directory rather then a * , you can {list,multiple,directories} if needed