I have been SEOing one of my sites for nearly two years now and one of the first things I did was submit to directories. It's been nearly two years and my link is found in three directories (mine being one of them.) I've submitted to at least 50 directories as well. So what happened? I was denied entrance (actually it's unlikely, my site is completely legal with no warez, etc.) Google can detect directories :X Google probably can detect directories. So what does this mean? Most directories on the internet run pre-built/cookie cutter scripts which makes it easy for Google to pick up on. The only directories that seem to be found in Google through a site search is custom built directories.
Yeah my own experience with directories isn't good. On the other hand blog commenting and forum signature drive more traffic. Some good directories like dmoz are helpful but relying totally on directory submission isn't wise strategy.
Well you got 3 links out of 50 directories 2 years ago. You have to imagine that a good amount of those 50 directories are gone now, and lets say some didnt accept your link. 3 of the remaining directories is not bad. A backlink is a backlink, just imagine if you would have submitted to 500 or even 5000.
They're still good, but only if submissions are automated or outsourced...if you're doing it manually it's waste of time.
I have one site that I submitted it to over 300 directories and I think 2 links show up in site explorer.