robots.txt can only be used to block robots, not to allow them - so in your example, the mediapartners-google bot (which is the one used for AdSense, not the indexing robot) is banned from accessing the list of directories. However, the rule applies only to that particular bot.
If you want to exclude all bots from that list of directories, then you simply need:
Thanks, that's what I was thinking. Apparently the google line is required for the Real Cities advertising we do, but I don't know how it helps google ad sense with anything since it is just disallowing it.
I'm still looking for clarification, though, on the * that appears in the line "User-agent: Mediapartners-Google*"
Does that star add all the other bots to the disallows? If not, what service does it provide in this syntax?