I do not think TIOBE chart is in any way fair comparison unless it subdivides area of use. Correct me if it does.
It is only natural that Ruby, Python etc. will be more popular overall because they are used not only on the web but also on the desktop on a very large scale. Web developers should not worry about popularity of PHP being to other languages because on the web it is still on top. The chart has no way to differentiate whether developers are looking for info on Python web service or Python desktop window - the latter is completely irrelevant to us.