Guess what? If you thought your robots.txt file wasn't being spidered by search engines, think again. Try the following in Google:
"robots.txt" "disallow:" filetype:txt
I'm sure you'll find a significant number of results.
Are you concerned about what content is going up? Then don't hide it under a disallow directive; just don't put anything up that you don't want search engines (or users!) to see.
If you're really concerned about your content, you can disallow these directories in your .htaccess, and that file is not accessible by search engines.
Forum discussion (it's a good one!) continues at Cre8asite Forums.