I just browse and read a little bit on http://googlewebmastercentral.blogspot.com/2007/04/indexar-o-seu-site.html and found an interesting post line that caught my eye on directories. Here is an excerpt

Use AdSense wisely. Monetizing original and valuable content will generate you more revenue from AdSense compared to directories with no added value. Be aware that sites without added value will turn away users from your site before they will ever click on an AdSense ad.

Look at the line “directories with no added value, I will not jumped right now on the conclusion that directories are really no added value at all. Besides google is using dmoz data on their directory. Or will this mean a few “chosen directories”? By then what will the ranging directory owners out in the internet world would do on their directories? Since most of it are monetizing their directories or so called “paid directories”. I know the statements above are to point on adsense system but taking into a closer look and analysis on the few lines seems google is starting to check directories and cracking it down on their engines.

There are instances that when you check your backlinks, google results are not not showing links on directories that much unlike previous backlink results. Maybe sooner google adsense rules will also state that “Adsense ads is not allowed to put on directories”. Just my 2 cents of it.