I found very difficult to filter the questions based on the programming language because most people forget to specify the language and they are using more specific tags like JQuery
but they forget to add JavaScript
tag.
People are forgetting that SO is a general purpose programming site and for this reason they are not adding the language tags.
It is not practically possible for users to add to ignore tags each sub-tags (i see language tags as major tags and the more specific ones as sub-tags).
I think that StackOverflow needs a system to auto-assign tags based on existing tags like.
hibernate
->java
jquery
->javascript
nhibernate
->.net
rake
->ruby
Using such a system would make the filtering by language/technology accessible.